The tax rates that you have defined will be automatically applied to Shopping Cart purchases, as well as sales orders generated from Shopping Carts containing items that can’t be purchased with a credit card. The application of tax rates is based on the address of the account, according to the regions for which you have specified tax rates.
Note that if no tax rates for a given region have been created, purchases and sales orders conducted through the Shopping Cart by customers located in the region will not have a tax rate applied to them.