I'm a small business owner in NC and I don't collect sales tax on some items even if it's out of state. However, if I collect sales tax I must submit it to the state. It's worth noting that it's always the responsibility of the customer to ensure they're complying with state and local laws regarding non-taxed sales, especially those made over the internet.
If I had bothered to actually read the confirmation e-mail I would have seen a disclaimer that reinforces this idea. Here's a disclaimer at the bottom of my recent order:
"Bearcatwarehouse is not required to and therefore does not collect sales and use tax in all states. This purchase is subject to state use tax unless it is specifically exempt from taxation. The purchase is not exempt merely because the purchase is made over the Internet, by catalogue, or by other remote means. Certain states require purchasers in those states to report and pay tax on any purchase when the purchase is not exempt and tax was not collected by the seller. The tax may be reported and paid on tax forms as prescribed by each state. These forms and corresponding instructions may be found on the applicable state's department of revenue/taxation websites."
Hopefully that puts an end to the tangent I started.