Here in the UK the price you see on the bill or price tag is the price you pay. Unless it is a service such as car repair or building where 20% VAT is added. So one of the most frustrating things for a UK visitor to America is going to the till with your $9.99 item and not knowing what the total bill be when you pay. There is city tax, state tax, local tax and it all differs depending on what you are purchasing and what state you are in. Some charge for everything, some charge for clothes, some charge for eating in restaurants. A very confusing picture to be honest.
This might help and it also might influence your destination decisions as well.
These states have no tax on certain clothing (usually items under a certain amount)
The average sales tax is usually between 6-10% and can be quite a shock if you are expecting to pay the ticket price.
Some states offer Tax Free Shopping arrangements for overseas visitors where you provide receipts for purchases and the tax you have paid is refunded eventually to you. This is usually for higher end purchases so check the information carefully in each location. Texas is an example of providing this service. I remember saving all my receipts happy in the knowledge I was going to get a refund as I left Dallas on my return flight. It was when I read the small print that it specified which stores were participating in the arrangement and not one of my choices was there…..not one of them. I would have had to shop upscale and designer which is definitely not my bag.