Adding VAT with hook

Hey,

I’ve been adding VAT to the price by using the ms_invoice_tax_rate hook. However I want this rate to be deducted from the price so that the total price is what I’ve added for the subscription rather than adding to the price (like an inverted discount). Is there a way to do this? My company is in Europe and I need to display the price with all taxes included. Every EU country has its own VAT rate.

So what I need to do is to add a VAT rate which could be different but in the end the same total should come out.

Example: Subscription is 10€. In Sweden the tax rate is 25% and in German 19%. The final price must NOT differ in both countries.

Is this possible to do with a hook? I’m using version 1.1.0.0 at the moment. Is this possible in a later version?