In the US it is not common to show a price after sales tax, like it is in Europe with VAT.
Also, not all states have the same amount of sales tax and some have no tax at all. It would be impossible to show the prices with sales tax when there are 50 different states with differing sales tax laws.
> It would be impossible to show the prices with sales tax when there are 50 different states with differing sales tax laws
Heck, the state level sales tax rates are even the easy part. Within states there are counties which often levy additional sales tax, and then cities within the counties do it as well. These county and municipal tax rates are additionally often comprised of a variety of "temporary assessments" which appear and expire seemingly at random. Knowing which rate is charged at a given location devolves into a very difficult problem once you realize there's no centralized address-to-jurisdiction database, nor a centralized jurisdiction-to-tax-rate database.
Funny thing (or not so funny, if you are small company), beginning next year you are required to do so in Europe. Amazon (AWS), Dropbox and alike have to indicate the tax (VAT) of the country the buyer is in and not anymore where the company is in-cooperated.
Current practice is, that the tax of the country, where the company is in-cooperated applies.
With that move, the EU wants, that every country is getting their share, and not like is now, that some countries are getting it. But this added bureaucracy is making it much harder for smaller companies.
