Paper money, dollar bill:
banknote

The slip of paper used to tell a customer how much money they paid or must pay; e.g. "Waiter, I'm done with my meal. Check, please!"
receipt, purchase_bill

Duck bill:
This tag appears not to be used. Some very obvious tags that show up everywhere just aren't used. E.g. we use not_furry for images that are not furry, but furry is invalid since >99% of images would have it anyway.