I live in a state that has not yet implemented a sales tax on mail order sales, but I understand something like 34 states now charge the tax

Some states even charge sales tax on the shipping

As an Ebay seller, I'm sure two-thirds of my buyers are paying the tax, but Ebay and PayPal have arranged it so I never see an invoice with it, and I do not have to pay the states. Ebay and PayPal handle the processing.