Taxing Sales

 I don't think a business should be required to collect sales tax unless they have a physical presence in that state and that state has a sales tax. Sales tax around the US is too confusing. Some places have a set state-wide sales tax and others have a sales tax based on the city or county. How is a business (especially a small one) supposed to know the sales tax of every other city, county and state in the country? There really should be a VAT system - in the places that currently have a sales tax - where you know exactly what you are paying for before you check-out (so a $1.00 item isn't $1.07 at the register, but is $1.00 at the register, etc.)