Sales tax is only charged on sales to the final customer. Resellers (aka, stores) are not charged sales tax. [EDIT: Note that a "reseller" is any individual or entity that has registered as a reseller with their state. This usually incurs an obligation to file a sales tax return at least annually.]
In contrast, VAT is levied on every participant in the chain of transactions. (Note that businesses can offset their VAT liability with the VAT they paid for services/goods received.)