I think what you have done is to change every instance to have incl. VAT & Delivery.
What I did in my own system was to remove the alter_currency_value.tpl within products.tpl, product_t.tpl and product.tpl files and added database labels for the incl.Vat. It then shouldn't effect the cart pages.
I had to customise the way xcart displayed VAT for my xcart, I now show the price exclusive of vat then beside it in less bold font, the price including vat. using the command lines below:
Code:
<td class=PriceExVat>{include file="currency.tpl" value=$product.price}{$lng.lbl_excluding_vat}</td>
<td class=PriceIncVat>{include file="currency.tpl" value=$product.price_vat}{$lng.lbl_including_vat}</td>