Modify prices calculation (product list, product page, shopping cart)

[Stefand]

HI,

Here in the Netherlands I work with the ECOTAX system. Right now in version 1.4.3 the ECOTAX is calculate include the product price. But is also displays below it.

So the prices in the product list, product page, shopping cart are include the ECOTAX.
When a customer see my prices include the ECOTAX it thinks; this shop is much expansiver than the other one (other shops here in the Netherlands show prices without the ECOTAX but when you checkout, then the final price to pay is include the ecotax.

So my question: Does somebody knows to modify the $orderTotal calculation ?