I just made an online order of a cell phone from Best Buy and the state sales-tax that was being applied initially seemed wrong so I contacted them in a "chat." I chatted with 2 different people and both insisted that Best Buy applies sales-tax based on the customer's billing address which is something I had never heard of.
I was having the phone delivered to New York so once I found out they charged based on billing address I called my bank and changed my billing address from my friend's address in Connecticut to my girlfriend's address in Oregon as OR has no sales tax (I am Canadian but use a US billing address for my USD Visa). Best Buy's online order form still did not represent the sales tax as the 0% of Oregon so I chatted again with Best Buy and they told me to place the order and they would refund the sales tax to my original method of payment. They sent me an email confirming that the sales-tax refund is in process and I'm just waiting to make sure that posts to my Visa account (I saved a copy of the chat for proof in case I do not get the refund).
I order a lot of things on Amazon and I always thought that when they did charge sales-tax it was based on the shipping address so perhaps Best Buy is anomalous. Obviously Best Buy has retail stores in every state but maybe it has to do with rules of the state in which the merchant is headquartered.
Your mileage may vary but if you are dealing with Best Buy's online ordering it would seem that this could be a way to avoid sales tax entirely.