I don't think there is a VAT or tax refund on exports from the United States, as tax is collected by each state and varies from state to state. However, Hermes will probably ship something to another state for you to save you some tax (for example, if you are in the NYC store, they will ship it to Connecticut to save you some tax).
Also, if you are bringining in merchandise to the US, you have to declare it in customs. If I recall correctly, the President's sister in law got in trouble for not declaring her purchases.