/**
  * Add tax data for tax totals for the merchandise prices and discounts.
  *
  * @return self
  */
 protected function _addMerchandiseTaxes()
 {
     $taxes = $this->_getTaxRecordsBySource(EbayEnterprise_Tax_Model_Record::SOURCE_MERCHANDISE);
     $discountTaxes = $this->_getTaxRecordsBySource(EbayEnterprise_Tax_Model_Record::SOURCE_MERCHANDISE_DISCOUNT);
     if ($taxes || $discountTaxes) {
         $priceGroup = $this->_orderItemPayload->getMerchandisePricing() ?: $this->_orderItemPayload->getEmptyPriceGroup();
         $priceGroup->setTaxClass($this->_itemProduct->getTaxCode());
         $this->_addTaxRecordsToContainer($taxes, $priceGroup)->_addDiscountTaxRecords($discountTaxes, $priceGroup);
         $this->_orderItemPayload->setMerchandisePricing($priceGroup);
     }
     return $this;
 }