Add field for saving rounding difference

README.md

@@ -5,10 +5,12 @@ Magento 5-Rappen-Rundung for Swiss Magento Merchants
 
 After installing the extension, please log out of your Magento backend and re-login, the go to 
 
-System > Configuration > General > Currency Setup > 5 Rappen Rundung
+_System > Configuration > General > Currency Setup > 5 Rappen Rundung_
 
 in order to enable the extension and set the rounding to either "All prices and totals" (including invoices) or "Totals only".
 
+The difference between the resulting (rounded) and the initial (unrounded) amount is saved to the column _rounding_difference_ in both quote and order tables.
+
 Credits:
 
 Thanks to Andreas von Studnitz (http://www.avs-webentwicklung.de) for providing the code basis and Michael Baer (http://www.codeag.ch) for sponsoring the extension.

app/code/community/Openstream/RappenRounding/Model/SalesQuoteAddressTotalGrand.php

@@ -16,6 +16,23 @@ public function collect(Mage_Sales_Model_Quote_Address $address)
         $grandTotal     = $address->getGrandTotal();
         $baseGrandTotal = $address->getBaseGrandTotal();
 
+        // at some circumstances the difference between rounded and unrounded totals can be caught on this place
+        $roundingDifference = 0.0;
+        /** @var Mage_Sales_Model_Quote_Item $item */
+        foreach ($address->getQuote()->getAllVisibleItems() as $item) {
+            $roundingDifference += $item->getRowTotalInclTax() - $item->getRowTotal() * (1 + $item->getTaxPercent()/100);
+        }
+
+        if (abs(round($roundingDifference, 2)) > 0) {
+            $address->getQuote()->setRoundingDifference($roundingDifference);
+        }
+
+
+        /* These totals if rounded are mostly wrong because they are excl. tax and tax is not rounded
+         * in the corresponding total. So it's actually a @fixme
+         * Rounding the total amount normally just corrects grand total
+         * It also makes no sense to calculate rounding difference here until tax total is fixed
+         */
         $totals     = array_sum($address->getAllTotalAmounts());
         $baseTotals = array_sum($address->getAllBaseTotalAmounts());
 

app/code/community/Openstream/RappenRounding/Model/TaxSalesTotalQuoteSubtotal.php

@@ -14,18 +14,45 @@ public function collect(Mage_Sales_Model_Quote_Address $address)
     {
         parent::collect($address);
 
+        $roundingDifference = $this->caculateItemRoundingDifference($address->getQuote());
+
         /** @var $helper Openstream_RappenRounding_Helper_Data */
         $helper = Mage::helper('rappenrounding');
 
         if($helper->getScope() == 'totals' || $helper->getScope() == 'all') {
+            // no need to calculate difference for base currency since we only need the end result
+            $roundingDifference += $address->getSubtotalInclTax() - $helper->_roundBase5($address->getSubtotalInclTax());
+
             $address->setSubtotalInclTax($helper->_roundBase5($address->getSubtotalInclTax()));
             $address->setBaseSubtotalInclTax($helper->_roundBase5($address->getBaseSubtotalInclTax()));
             $address->setTotalAmount('subtotal', $helper->_roundBase5($address->getTotalAmount('subtotal')));
             $address->setBaseTotalAmount('subtotal', $helper->_roundBase5($address->getBaseTotalAmount('subtotal')));
         }
 
+        $address->getQuote()->setRoundingDifference($roundingDifference);
+
         return $this;
     }
 
+    /**
+     * Calculate difference between unrounded and rounded row totals
+     *
+     * @param Mage_Sales_Model_Quote $quote
+     * @return float
+     */
+    protected function caculateItemRoundingDifference($quote)
+    {
+        $difference = 0.0;
+
+        /** @var Mage_Sales_Model_Quote_Item $item */
+        foreach ($quote->getAllVisibleItems() as $item) {
+            $difference += $item->getRowTotalInclTax() - $item->getPriceInclTax() * $item->getQty();
+        }
+
+        $quote->setRoundingDifference($difference);
+
+        return $difference;
+    }
+
 
 }

app/code/community/Openstream/RappenRounding/etc/config.xml

@@ -2,7 +2,7 @@
 <config>
     <modules>
         <Openstream_RappenRounding>
-            <version>0.2.2</version>
+            <version>0.3.0</version>
         </Openstream_RappenRounding>
     </modules>
     <global>
@@ -26,11 +26,25 @@
                 </rewrite>
             </sales>
         </models>
+        <resources>
+            <rappenrounding_setup>
+                <setup>
+                    <module>Openstream_RappenRounding</module>
+                </setup>
+            </rappenrounding_setup>
+        </resources>
         <helpers>
             <rappenrounding>
                 <class>Openstream_RappenRounding_Helper</class>
             </rappenrounding>
         </helpers>
+        <fieldsets>
+            <sales_convert_quote>
+                <rounding_difference>
+                    <to_order>*</to_order>
+                </rounding_difference>
+            </sales_convert_quote>
+        </fieldsets>
     </global>
     <adminhtml>
         <translate>

app/code/community/Openstream/RappenRounding/sql/rappenrounding_setup/upgrade-0.2.2-0.3.0.php

@@ -0,0 +1,24 @@
+<?php
+/* @var $installer Mage_Core_Model_Resource_Setup */
+$installer = $this;
+$installer->startSetup();
+
+$installer->getConnection()->addColumn(
+    $installer->getTable('sales/quote'),
+    'rounding_difference',
+    [
+        'type' => Varien_Db_Ddl_Table::TYPE_DECIMAL,
+        'length' => '12,4',
+        'comment' => 'Difference between rounded and unrounded grand total'
+    ]
+);
+
+$installer->getConnection()->addColumn(
+    $installer->getTable('sales/order'),
+    'rounding_difference',
+    [
+        'type' => Varien_Db_Ddl_Table::TYPE_DECIMAL,
+        'length' => '12,4',
+        'comment' => 'Difference between rounded and unrounded grand total'
+    ]
+);