As far as I have experience with these, taxes such as SST (States Sales Tax, each can have different rates based on the states i.e. California – 7.25%) so what happens is that these are direct (automated by Amazon) customer pays and Amazon charges without your involvement in the case so you need not increase your price for paying the tax, on the other-hand VAT, is a process (everyone involved in the order is obliged to pay VAT) customer pays the VAT to your and you pay it to the state (country) also it is fixed (21% in UK) so if your VAT (needed to pay amount) is £5 you’ll up your price by that Amazon charges it from you, and you charges it from the customer, there is only the way it works and percentage, etc. though they all are a form of taxes.