VAT Calculation on eCommerce

At the moment VAT (or any other Tax) is worked out on an individual product basis and rounded up or down. This creates an issue when calculating the final total as any rounding is multiplied causing the gross figure to be out. This is fine for single product purchases but not when you're ordering multiples. The Calculation should be net individual price x qty ordered = total net x VAT rate = Total Payable ie done on a line basis or even a basket basis. We need the option to choose how this is worked out and pull the right liquid tags into the cart.