As of now, online retailers are artificially keeping their prices lower by not charging tax to their out of state customers but it's just a matter of time before all online businesses will be charging tax upfront. Technically, you are obligated to pay the taxes on anything you purchase out of state, but most online businesses leave it up to the purchaser. If you are visiting a different state and purchase at a brick and mortar store, you do not have to pay taxes at that point or you can opt to pay the tax rate of your home state. It may be a pain to try and explain that to the person at the counter, but technically you should be able to do this as long as you can furnish an out of state ID. I used to work in IT for a retail chain and had to program the registers to they would be able to accomplish this although it was a rarely used feature. When traveling out of the country, many places will make you pay upfront, but before you leave, you get a tax refund based on your receipts.