At first glance Sales Tax looks a lot similar to VAT, but believe me it is a totaly differnt world.
The core difference is responsibility.
With VAT, the buyer pays VAT, and then at the end of the month fills in a report that allows them to claim back VAT. If soemthing goes wrong, then the buyer, the customer is the person that gets into problems.
With sales tax, the Seller is responsible for paying the tax, and even if for example the customer gave them wring information, its stil the vendor that pays the fines and has the problems.
So this very simple difference leads to all the issues in differences.
In the UK you have maybe 4 tax rates, and one reporting body. In the US you have tens of thousands of rates, and thousands of reporting authorities. Some complex places like LA, Atlanta and Dallas have up to four taxes on an item, and you even have some towns that can charge different tax depending on the street number of the building you deliver to. (OK that’s extreme and rare, but it happens).
Anyway. If you are going to implement Sales Tax, you really want to do it with someone that knows what they are doing. It really is vastly more complex than VAT, and your customer will pay for any mistakes made. PS one hint, to get started, use Zip codes as the Tax Area code, since that is the way most tax service providers are going.
Oh and if all this sounds complex, you just gotta see how they do it in Canada.