As it now stands, I believe the law excludes merchants with less than $1 million in annual sales in the state unless they have nexus. This is a fairly high threshold --maybe even too high-- but seems like a reasonable start.
BTW, the way most -if not all- taxing states work, the sales tax is a misnomer. It's a USE tax and you are supposed to pay it as an individual even if the merchant didn't collect it.
In NC, it's on your state tax return.