Tax free

Stores in the USA typically do not concern themselves with foreign tax laws. They operate in accordance with the tax laws applicable to them. Which means you pay taxes as required by the State in which the store is located.

I believe you need to get that from the state in which you made the purchase - see the information here (including the links on that page):

https://help.cbp.gov/app/answers/detail/a_id/373/~/how-to-obtain-a-refund-of-sales-tax-paid-while-visiting-the-united-states

Also note: going that route may also result in your country charging an import tax on the purchases which may be the same amount (or more) than the sales tax you saved.