on bigger business transactions, i don't know how it works here. My mother was a craft circuit person for 40 years. I do know for sure that she didn't pay sales tax on her supplies, but her buyers paid sales tax on the entire cost.
Which she end-arounded being problematic in person (mostly for change collecting reasons) by putting up a sign that said "all prices include sales tax".
There absolutely ARE state tax agents who pose as buyers at craft shows to see if you're charging tax, and they don't love that sign, but it's not illegal. They don't love it because they want you to make their job easy by saying "it's $10, we don't collect sales tax", which is not allowed.
When my mother did most of her selling, it could be fast paced at a fast show, selling $5-$20 items and sometimes $6-$8k in a weekend at the better shows. It was worth it to make the prices with tax a round figure and then go back later and back into the calculation of what was payable to the state tax authority, which they then did. Having change on hand for that kind of a volume is a real problem.