Then why not just add it on to advertisements etc? For tourists it's pretty confusing, espescially if you suck at Maths.
Not that simple
In Pheonix metro, each city has it's own tax. Add the tax for the county and the state. And different county May have different rate. For the same cup of starbuck coffee, you may pay different price in the other starbuck just across the street
I live in Scottsdale which tax grocery at 1.65% and consumer goods at 8.95% (including tax at all levels) while in Phoenix, grocery is 2% and overall for consumer goods 9.3%. But the Chinese supermarket In Mesa has no grocery tax but the others in Peoria and Chandler have.
It's just very complicated