Maybe you should pay your car license fees with pennies and find out if you’re correct. The “Pennies are money” argument usually loses, especially in government offices.
Most would take a fistful of Susan B. Anthony dollars, though. Anyhow if it isn’t in the code, it would be a technical loser, though the cost to prosecute it might be way more than the fine.
That would be an interesting tact to take against the Federal Reserve.
The messenger does not have more authority than the one who sends him, and therefore the one to whom a job is delegate cannot be greater than the one who delegated that job in the first place — therefore, refusing to accept coinage minted by the Treasury and yet accepting Federal Reserve notes presents a contradiction: for the government (the Treasury) has both the responsibility and right to coin monies, but the printing of "federal reserve notes" is a delegated position from the government.
So, which is the greater authority: the Treasury, or the Federal Reserve?
And if you claim the Federal Reserve, then from whence comes its authority?