I very much doubt that this is legal in CO. I can think of a few states where this might pass muster, but CO is not one of them.
However, it is also true that you can be fired for making too many mistakes. Is an incentive to check your work really that bad an idea?
FYI, you do not have a claim with the wage and hour people until someone actually is fined. A threat of potential fining is not enough.
Two things I am tired of typing: 1.) A wrongful termination does not mean that you were fired for something you didn't do; it means that you were fired for a reason prohibited by law. 2.) The above answer, whatever it is, assumes that no legally binding contract or CBA expressly says otherwise. If it does, the terms of the contract apply.