Go to a bank and ask for a $500 or $1000 note too. They won’t give you one as they aren’t in circulation anymore, but most (all?) will let you deposit it for face value.
It goes without saying that half pennies are dead. A mill seems to be from the Coinage Act of 1792, which is perhaps a tad outdated.
> A mill ... is perhaps a tad outdated.
Yet you use mills every time you pay for gas. Pointless in that case? Probably. Still used all the time? Certainly.