Product Fixed Gross Prices

Question

All of our product prices are stored as gross and have a related tax class. As per Mage's standard calculations the tax rate is added to the product's net value to calculate the product's gross price. I want to change this so that the gross price of the product is always the price the customer is charged regardless of the address the order is being shipped to (and its associated tax rate).

An example:

If a product's gross price is set at £26.50 and the customer has specified a UK shipping address (tax rate 20%) the price is broken down (and displayed) like so:

GB Address (tax rate 20%)
Product Price:  £26.50
Product Tax:    £4.42
Order Gross:    £26.50

However, if the customer then changes their delivery address from a UK address (tax rate 20%) to a Spanish address (tax rate 21%) then the gross price for this order is re-calculated like so:

ES Address (tax rate 21%)
Product Price:  £26.50
Product Tax:    £4.64
Order Gross:    £26.72

My question is; is it possible to configure Magento to not increase the gross price when the tax rate changes? All I want to do is inform the customer as to what £ value of the product's gross price is taxable (not increase the product's price).

So the ES Address order would calculate like this:

ES Address (tax rate 21%)
Product Price:  £26.50
Product Tax:    £4.64
Order Gross:    £26.50

Answer 1

This can be easily done with new "Cross border sells" feature (added in 1.9 I believe): http://merch.docs.magento.com/ee/user_guide/tax/tax-cross-border-price.html