and while we're at it, include the taxes!
Clarification: Many "essential" goods like simple foods are GST exempt. They will be marked as such on the receipt. Again, the price on the shelf or box is what you will actually pay. There are no hidden surprises.
Though there are still some special cases where they sneak in extra taxes - stamp duty on houses and import duties on cars for example.
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.
Canadians also have a Federal GST, and provinces add their own tax, which gets added together into one Harmonized Services Tax (HST) in all provinces but Quebec and British Columbia, which have their own rules (QC collects an additional Provincial Sales Tax (PST))
Of course, there are fun additional taxes as well like the Environmental Handling Fee (EHF) on electronics.
You can't assume "everybody" knows.