The question of sales taxes internet sales that cross state lines has indeed been settled by the Supreme Court, but in my state the legislature passed a law designed along the lines of the South Dakota statute that was upheld by SCOTUS that only requires out of state retailers to collect our states sales tax if their annual sales to our residents exceed $500,000. There is also now a conflict in how that statute allocates revenues that come in between cities and counties and our previously existing general sales tax statute, a problem that apparently our Revenue Commissioner has said will require the legislature to fix.
Until the $500,000 threshold is lowered, most of the internet vendors I buy from won't have to collect sales tax for sales made to my state. I do expect that the threshold will be lowered, but it might well take a year or so, and even then some on line vendors might still not do enough business here to be required to collect the tax. Unless and until Congress acts to create uniform rules, I expect the answer to whether or not you will have to pay sales tax on your on line purchases to be "it depends." I just ordered from Smoking Pipes, no taxes were added.