According to the Supreme Court a seller can not charge a sales tax on items shipped to a buyer in another state if that seller has no presence in the buyer’s state. So, if I purchased an item from Sears, Sears would add sales tax from that state, because Sears has a store in Nevada, but if there is no Sears store in that state, no sales tax. As for the FFL holder, he is preforming a service, and there is no sales tax on services in Nevada.