Students sometimes ask if it is possible for them to receive a refund of the sales tax they paid for goods and services in the United States upon their departure. In the U.S., sales tax on goods and services is set by each of the fifty states, and state entities (such as cities and counties), not by the U.S. government. Each state and state entity determines what the sales tax will be (always a percent of the purchase price) and what items will and will not be assessed a sales tax.
Therefore, it is not possible for an overseas visitor to obtain a refund of the sales tax for a purchase made in the U.S. upon their departure. The best "official" explanation comes from the U.S. Customs Service, which is reprinted below. Go to: http://www.customs.gov/travel/visi.htm# for additional information.
"Foreign visitors to the United States frequently confuse the state sales tax with the value-added tax (VAT). The state sales tax is a small tax on purchases or services, calculated at the time of purchase, which individual states assess and which the U.S. federal government neither determines nor receives. The VAT, on the other hand, is a national tax commonly applied in foreign countries that is included in the actual sales price rather than at the time of purchase. The United States does not have a VAT, and the federal government cannot refund state sales taxes.
State taxes are generally not charged to diplomats or employees of some international organizations who have been issued a tax-exemption card. This card must be presented at the time of purchase in order for sales taxes to be waived.
Also, many states do not charge tax on items shipped out of state. Ask about state sales-tax policies in the state where you make your purchases."