Honestly, I would pick it up. But I would look around and see if anyone seemed to be looking for it. Also, if it was found right outside a store, would probably go in and ask if anyone reported losing anything.
Beyond that, I would use it to help someone in need, if the opportunity presented itself. $100 is not THAT much money. Of course, if I found a bag or wallet or something with several hundred or $1000 or something like that, I would turn in to the police. But for just a mere $100, naw, I'd pick it up, and use it to help someone else if possible.
S
