Add product tax as normal product price for shipping method

Question

Here is example with problem explanation:

1. There is a product with base price $75 in Magento store
2. This product has tax (included in price by dynamic tax) $10
3. Where customer see product and adds it to the cart (and in checkout), product's price is $85 (base price + tax)
4. There is Webshopapps Matrix rates (free) installed in Magento store
5. Webshopapps Matrix rates configured to give free shipping for customer when product in cart costs $80 or more.
6. When customer goes to checkout, he can't use free shipping, because real product price (without tax) is $75.

What i need to get:

When customer goes to checkout, he must get free shipping for this product. This means, that Shipping method cost (Matrix rates carrier) must be calculate not product base price, but product base price + tax, eg: product base price is $75 and tax is $10, in this way, shipping carrier must use price $85, not $75.

How can i do this?

Answer 1

I found the solution!

In Carrier model (Webshopapps_Matrixrate_Model_Carrier_Matrixrate) i changed $request->getPackageValue() to the sum of grand total prices. Watch out! In quote may be duplications. Here is solution code:

$grandTotal = 0;
$ids = array(); //$request->getAllItems() has duplicates, we need to remove them
foreach ($request->getAllItems() as $item){
    if(!isset($ids[$item->getQuote()->getEntityId()]) || empty($ids[$item->getQuote()->getEntityId()]))
    {
        $ids[$item->getQuote()->getEntityId()] = true;
        $grandTotal = $grandTotal + $item->getQuote()->getGrandTotal();
    }
}

if ($this->getConfigData('enable_free_shipping_threshold') && 
    $this->getConfigData('free_shipping_threshold')!='' && 
    $this->getConfigData('free_shipping_threshold')>0 &&
    $grandTotal>$this->getConfigData('free_shipping_threshold')) { //here i changed $request->getPackageValue() to $grandTotal
        $freeShipping=true;
}