Is it 10% in all states?
In Canada, the provincial sales tax differs in each province. The federal rate is 5%. Alberta has no sales tax, whereas Ontario charges 8% (post-harmonization it's a HST of 13%).
In the US, the sales tax differs not only by state, but by county and city.
The tax situation in Chicago is particularly bizarre.
The sales tax in Cook County, where the city of Chicago located, is 10.25%. The sales tax one county over (say Dupage County, 15-20 miles outside the city and still part of the greater Chicago metropolitan area) is 8%.
Restaurants in the City of Chicago (but not other parts of Cook County) charge 10.75% because there's a city-specific restaurant tax.
The different tax rates create strange arbitrage opportunities. If I buy an iPhone from an Apple Store a few miles outside Chicago, I get an automatic 2.25% discount.