To set up your cart's sales tax, go to Shopping Cart >> Tax >> List Tax Rates.

Note: Generally, you will need to collect sales tax only for those items shipped within your state, but not all states are the same, and the laws may change. You need to check the rules that apply to your own state!

In the Tax Rate Listings, taxes are defined by country and state.
 

To Create a New Sales Tax Listing, click on the New button.

Next, select the Country, the State, and enter the percentage.

Percentage is set in a decimal format: 7.5% is 0.075.

Note: If you do not see your State or Region in the default list (e.g Puerto Rico), you may need to first Add a New State to the Country List.

Click the Save button.

Note:  If you need more advanced tax settings, please see the tax help page