If I pick up an item that claims to be $1.99, and plunk it down on the counter with $2, I don't want the cashier to say "That'll be $2.16, please." The label says $1.99 . They could have added the tax when they printed it. If they wanted the label price to be $1.99, they could have made the base price $1.83, and added the tax back in to make it $1.99 on the shelf.
If I go to a concession stand at a ball game, their list prices are all-taxes-included. $2 for a hot dog means if I ask for a hot dog, and pay $2 exactly, no one needs to mess around with change. Why can't other merchants do that?
It's not like consumers can just choose to stop buying things if the sales tax goes up. "What's that? Sales taxes went from 8.75% to 9.15% ? Oh, never mind, then, I'll just stop buying anything from here on out."