CS-Cart Delivery VAT product options.

The current CS-cart 2.x TAX / VAT options only allows one VAT rate per product. Within a product option for "size" currently cs-cart only allows a modifier for price and a modifier for weight. We need a modifier for VAT rate. So for example a Jacket comes in fours sizes, the first three sizes are 0% VAT but the extra large is 21% Small - > VAT rate 0%, Medium - > VAT rate 0%, Large -> VAT rate 0%, Extra Large - > VAT rate 21%. The selling price on the shop front needs to show the VAT inclusive price , so therefore the price selling would increase if the customer selected the "Extra Large" size. The options could be either Global options or product specific. The options/modifiers need to be available for use in the cs-cart import/export options too.