The law forever has been if the store has an outlet in the state being shipped to then tax is charged at the amount the receiving state customarily charges. For instance, when I lived in TN when I bought something from Macy’s and shipped it I had to pay tax, because we have Macy’s in TN. If I bought something from Bloomingdale’s and shipped it, I didn’t have to pay any tax, because there is not a Bloomingdale’s in TN.
There was a new law out there to always charge sales tax at the amount the receiving state charges at point of sale. I don’t know of that law passed. If it did I know there are people trying to change it. If it hasn’t been voted on yet I know people are trying to block it.
If it is still the old way as I described in paragraph one, there are plenty of businesses that don’t understand the law and always charge tax. There are also businesses who don’t undertsand the current laws and don’t charge tax even when they should.