workaround in case if item subtotal precision is not compatible with PayPal (.2)

SUPEE-991_EE_1.12.0.2_v1.patch

diff --git app/code/core/Mage/Paypal/Model/Cart.php app/code/core/Mage/Paypal/Model/Cart.php
index 999d3b8..4d625ca 100644
--- app/code/core/Mage/Paypal/Model/Cart.php
+++ app/code/core/Mage/Paypal/Model/Cart.php
@@ -281,9 +281,11 @@ class Mage_Paypal_Model_Cart
 
         // regular items from the sales entity
         $this->_items = array();
+        $excludeTaxSum = 0;
         foreach ($this->_salesEntity->getAllItems() as $item) {
             if (!$item->getParentItem()) {
                 $this->_addRegularItem($item);
+                $excludeTaxSum += $item->getExcludeTax();
             }
         }
         end($this->_items);
@@ -294,8 +296,8 @@ class Mage_Paypal_Model_Cart
         if ($this->_salesEntity instanceof Mage_Sales_Model_Order) {
             $shippingDescription = $this->_salesEntity->getShippingDescription();
             $this->_totals = array(
-                self::TOTAL_SUBTOTAL => $this->_salesEntity->getBaseSubtotal(),
-                self::TOTAL_TAX      => $this->_salesEntity->getBaseTaxAmount(),
+                self::TOTAL_SUBTOTAL => $this->_salesEntity->getBaseSubtotal() + $excludeTaxSum,
+                self::TOTAL_TAX      => $this->_salesEntity->getBaseTaxAmount() - $excludeTaxSum,
                 self::TOTAL_SHIPPING => $this->_salesEntity->getBaseShippingAmount(),
                 self::TOTAL_DISCOUNT => abs($this->_salesEntity->getBaseDiscountAmount()),
             );
@@ -305,8 +307,8 @@ class Mage_Paypal_Model_Cart
                 $this->_salesEntity->getBillingAddress() : $this->_salesEntity->getShippingAddress();
             $shippingDescription = $address->getShippingDescription();
             $this->_totals = array (
-                self::TOTAL_SUBTOTAL => $this->_salesEntity->getBaseSubtotal(),
-                self::TOTAL_TAX      => $address->getBaseTaxAmount(),
+                self::TOTAL_SUBTOTAL => $this->_salesEntity->getBaseSubtotal() + $excludeTaxSum,
+                self::TOTAL_TAX      => $address->getBaseTaxAmount() - $excludeTaxSum,
                 self::TOTAL_SHIPPING => $address->getBaseShippingAmount(),
                 self::TOTAL_DISCOUNT => abs($address->getBaseDiscountAmount()),
             );
@@ -423,27 +425,38 @@ class Mage_Paypal_Model_Cart
      */
     protected function _addRegularItem(Varien_Object $salesItem)
     {
+        $subAggregatedLabel = '';
         if ($this->_salesEntity instanceof Mage_Sales_Model_Order) {
             $qty = (int) $salesItem->getQtyOrdered();
             $amount = (float) $salesItem->getBasePrice();
+
+            $rowTotal    = $salesItem->getBaseRowTotal();
+            $priceIncTax = $salesItem->getBasePriceInclTax();
+            $taxAmount   = $salesItem->getBaseTaxAmount();
             // TODO: nominal item for order
         } else {
+            /**
+             * now we have quote - regular place order process
+             */
             $qty = (int) $salesItem->getTotalQty();
             $amount = $salesItem->isNominal() ? 0 : (float) $salesItem->getBaseCalculationPrice();
-        }
-        // workaround in case if item subtotal precision is not compatible with PayPal (.2)
-        $subAggregatedLabel = '';
-        if ($amount - round($amount, 2)) {
-            $amount = $amount * $qty;
-            $subAggregatedLabel = ' x' . $qty;
-            $qty = 1;
+
+            $rowTotal    = $salesItem->getRowTotal();
+            $priceIncTax = $salesItem->getPriceInclTax();
+            $taxAmount   = $salesItem->getTaxAmount();
         }
 
-        // aggregate item price if item qty * price does not match row total
-        if (($amount * $qty) != $salesItem->getBaseRowTotal()) {
-            $amount = (float) $salesItem->getBaseRowTotal();
-            $subAggregatedLabel = ' x' . $qty;
-            $qty = 1;
+        /**
+         * aggregate item price if item qty * price does not match row total
+         * workaround in case if item subtotal precision is not compatible with PayPal (.2)
+         */
+        $salesItem->setExcludeTax(0);
+        if (($amount * $qty) != $rowTotal
+            || ($amount - round($amount, 2))
+        ) {
+            $amount = $priceIncTax;
+            $subAggregatedLabel = Mage::helper('tax')->__(' (Incl. Tax)');
+            $salesItem->setExcludeTax($taxAmount);
         }
 
         return $this->addItem($salesItem->getName() . $subAggregatedLabel, $qty, $amount, $salesItem->getSku());