I can tell you that keeping bills in a metal tin does not allow any air circulation and therefore condensation can build up and make notes musty, damp, and even mouldy. The big problem is that if they are damp the notes tend to get wavy as well.
You could try putting them in a container with silicate packs or baking powder to see if that absorbs some or all of the smell. As for value, I am sure that it will affect price especially if the smell remains.
Even a safe if not opened to let air circulate will make a new bill musty, damp and smell. If you ever left a piece of paper or cardboard on a cement floor for a while and then picked it up you can already see how it absorbed the dampness.
[edit]Removed libellous reference against another member of the forums. --BWJM[/edit]