Someone is Stealing

We have a change bag at the LBH where we store a little cash and coin for moments when we need to replenish the cash registers. In the last several months we have had it come up short every now and again. Usually that leads us to find that someone took out a roll of quarters but did not put $10 in to pay for it, leaving the bag short. There have been times when the missing amount is more significant and doesn't get caught on the drawer count and then deposited.  Okay.  When the bag balances out the night before and then comes up $120 short tonight and the drawer shows $.68 positive, well, that is a problem.  This scenario has happened a few time also.  The last time I found it we were $110 off.  I implemented a few things then and that is why I got a phone call tonight.  Now I am implementing another part of the process and this should allow us to pinpoint when the money went missing.  Really what I need is a camera system.