They'll have to give up using federal currency then, because every US dollar has printed on it that it is property of the department of the US treasury, and of course is minted by the treasury.
So in actuality every physical dollar bill or coin is the property of the government, and is simply leant to individuals who choose to use their currency, therefore libertarians of course cannot claim that the money is their property, since it isn't; in the American revolution of course, the property being accused of unfair taxation was not fiat currency manufactured by a government, but actual hard goods.
If they want independence then they'll have to give up using US dollars and create their own currency; national US currency is a fairly recent invention anyway