Magento: tax deducted instead of added

Question

My excluding tax amounts are treated as if they are including tax. Now I know you would say I've my settings messed up but they are correctly set on excluding tax. If I enable the tax settings for the row it does show 10 jeans for 10 euro each, makes a 100 euro ex and 119 (19% dutch tax) including tax.

Example:

Subtotal:           100
Shipping:           50
Grand Total ex:     121,5
TAX:                28,5
Grand Total In:     150

I've found one other case with the same problem but sadly enough no answer... http://www.magentocommerce.com/answers/Catalog-prices-do-not-include-tax-but-if-I-check-excluding-tax-my-prices-change

CopyPaste example

Subtotal (Excl. Tax)    € 65,20
Subtotal (Incl. Tax)    € 77,59
Shipping Excl. Tax (Flat Rate - Fixed)  € 50,00
Shipping Incl. Tax (Flat Rate - Fixed)  € 59,50 
Totaal Excl. BTW    € 93,31
BTW € 21,89
Totaal Incl. BTW    € 115,20 

Answer 1

It is far far far from pretty, but the following works!

19% is the dutch tax amount

class Mage_Sales_Model_Quote_Address_Total_Grand extends Mage_Sales_Model_Quote_Address_Total_Abstract
{
    /**
     * Collect grand total address amount
     *
     * @param   Mage_Sales_Model_Quote_Address $address
     * @return  Mage_Sales_Model_Quote_Address_Total_Grand
     */
    public function collect(Mage_Sales_Model_Quote_Address $address)
    {
        $grandTotal     = $address->getGrandTotal();
        $baseGrandTotal = $address->getBaseGrandTotal();

        $totals     = array_sum($address->getAllTotalAmounts());
        $baseTotals = array_sum($address->getAllBaseTotalAmounts());

        $address->setGrandTotal(($grandTotal+$totals) * 1.19);
        $address->setBaseGrandTotal(($grandTotal+$totals) * 1.19);
        return $this;
    }

    /**
     * Add grand total information to address
     *
     * @param   Mage_Sales_Model_Quote_Address $address
     * @return  Mage_Sales_Model_Quote_Address_Total_Grand
     */
    public function fetch(Mage_Sales_Model_Quote_Address $address)
    {
        $address->addTotal(array(
            'code'  => $this->getCode(),
            'title' => Mage::helper('sales')->__('Grand Total'),
            'value' => $address->getGrandTotal(),
            'area'  => 'footer',
        ));
        return $this;
    }
}