I addressed in another reply that "'none' is all that's necessary" is probably a defensible interpretation of the law (the more relevant portion being in 5111 rather than 5112), but the penny being explicitly listed makes it clearly not the intention of congress. That's why I said it's a "shaky" and not "baseless" legal ground. The law is clearly written with the expectation that there will be some, which is why Congress felt the need to pass the Coinage Act of 1857 to phase out the half cent.

I think we should get rid of the penny, but it's Congress's responsibility to do that, and they haven't. I'm opposed to Congress abdicating its power and responsibility like that.

You're right, 5111 is more pertinent here.

5111(a)(1) says “shall mint and issue coins” but qualifies it explicitly with “in amounts the Secretary decides are necessary to meet the needs of the United States”. This is a clear delegation of authority.

If you don't think zero pennies is a permissible amount, what about one penny? Two? What minimum number are you arguing for here, and what's your justification for it?

If Congress had wanted to set a minimum number, they could have done so.

Reading it as ”shall mint” is wrong, I think. “Shall” qualifies the whole clause “mint in amounts the Secretary decides (etc.)”.

Understood that way, 5111 makes it unlawful to mint any pennies if the Secretary decides that none are necessary.