State and local (county and/or city) tax on goods varies from zero to close to 10%. States charge the lion's share, with local taxes usually in the 1.0-1.5%. For instance, ST in Chicago breaks down as follows:
Illinois State 6.250%
Cook County 1.750%
City of Chicago 1.250%
Larger urban areas typically have higher local tax rates, but it seems the smaller cities are catching up. Services are not taxed in Illinois, but there is talk about doing so.
Retailers are generally not forced to collect it unless they have some sort of presence within the state it is purchased from. In Illinois you are supposed to keep track of purchases made from out of state, then account for the sales tax you should have paid in your state income tax filing. I would guess compliance with that is about 0.01%. Local retailer groups have been lobbying for an "Amazon" tax (forcing online retailers to collect sales taxes from all customers) citing unfair competition. I'm sure that plays a part, but I believe convenience and good selection play a big part in online purchases and local stores won't see much effect from an Amazon tax. As governments always need more money to save the poor and the children I'm sure the Amazon tax will arrive sooner or later.
A VAT is ocassionally discussed at the national level but it hasn't got very far...yet.