Sales tax is a flat tax within a state, but it's wildly variable from state to state - Delaware has none, Maryland has ~6%, NY has over 8%. I think a percentage

Sales tax is a flat tax within a state, but it's wildly variable from state to state - Delaware has none, Maryland has ~6%, NY has over 8%. I think a percentage agreed upon by all states is probably the agreement they mentioned, but I don't think they had enough detail to confirm it.