In “common” Québec French we call the one-cent coin "une cenne noir" - a black penny. Pennies used to become black with age. When a single penny used to be worthwhile currency, a poor person would have tried to save his pennies - blackening with age - to be able to buy something.
Our coins are identified by the quantity of pennies. For example, we don't say a quarter or a dime, we say "do you have a twenty five pennies" or "a ten pennies".
We use an expression "pay to the last black penny" (payer jusqu'à la dernière cenne noir) when we want to convey that we paid something in full (what we owed is completely paid back) Oh, it is important to add that this is usually said when there is some argument as to whether the debt was paid...like when somebody says "Eugene says you never gave him his ten bucks back."
We also say "it cost me to my last black penny," (ça m’a coûté jusqu’à ma dernière cenne noir) to mean it took all the money we had to buy something - we don't even have a meager penny left.
