In the United States, there is no uniform GST or VAT, and amount of tax a buyer will pay depends on the individual state. In case of online shopping, the amount of tax depends on the state where the goods are shipped to and adds 7-10% (and up to 15% for goods that are considered luxury).
Now good news:
So you can ship clothes, shoes and most orders directly to Pennsylvania and electronics, cosmetics, home goods, etc. to Delaware and pay no US sales tax whatsoever!