One of my favorite FFLs does!
Our sales tax folks say that the gun is "sold" when the customer fills out the 4473, and the background check says the customer can take the firearm.
So, since that's the point of the sale, and it's in Florida, there's sales tax to be collected.
Two other FFLs, both personal friends, don't.
But, with the shortage of moneys at the state level, they figure they are just living (or the customers are) on borrowed time and, when the sales tax folks come calling, they'll be forced to change their policies.
Now, any of us can beat on our chests and swear the sale took place in the state where the original seller lived and got the money for the gun, but, as to the FFLs, if the sales tax folks threaten them with penalties, etc., they are gonna collect the tax.
Our state already "requires" places like Lands End to collect sales tax (though I don't know if they still do since I haven't bought anything from them for about ten years).
Bob