United States of America – Official VAT-Refund Rules (Tourists)

• There is no national value added tax (VAT) in the USA and therefore no nationwide tax/duty-free system
  • The US federal government does not refund sales tax to tourists.
    • Only two states offer a genuine refund system for international tourists: Texas and Louisiana (minimum purchase: varies depending on the store (typically USD 12–50 per receipt))
• The following states do not levy sales tax and therefore do not offer refunds:
  •  Oregon
  • Montana
  • Delaware
  • New Hampshire
• Duty Free is a separate system that only applies to goods that you can buy directly at the airport (savings of up to approx. 10%)

Source:  How to Get a Sales Tax Refund for Foreigners in the USA - LegalClarity

No guarantee can be given for the correctness of the information about the VAT-Refund Rules in United States of America.