sales tax

Hi I have tried to modify the sales tax but have I noticed that the price of the product remains always the same excluded the possible tax that I would want to apply Who explains me how to do?
to make to appear the price with the tax

please send me an email with your site name, what state/country you want to charge taxes, and the tax rate.

Thanks
Mark

Quick note: Sales tax only applies to online payment orders, which as of now means paypal orders only.
Quote orders are not subjected to that value