nisht is correct that if you make online purchases from merchants (Amazon, Newegg, etc.) and they don’t bill sales tax in your State, then every year when you file your State taxes you need to pay the sales tax (also called use tax) that you didn’t pay for all the purchases the previous year from merchants that didn’t bill your State’s sales tax.
Does everyone here who is judging others declare all their out-of-state online purchases on their state tax return that they didn’t pay sales tax at the time of the sale? Otherwise you’re a tax cheat.