Tiaras and Trucks: reward system

A friend of mine posted a new reward system that she was doing, and it sounded interesting, and like something that I could actually manage to do! we modified what she did a little, but here is what we came up with.
Each child starts with $2.50 in dimes in their jar. If they are disrespectful, disobedient, or unkind then they lose a dime. This goes on for 1 week, and at the end of the week we count up the dimes and they turn them in for dollars or "real money" as caleb puts it.
This system has worked for us so far in that I dont feel like I am yelling as much.....instead, if one or both of them is being nasty all I say is thats 1 dime, or I just walk over and take 1 out of their jar....they dont always handle that well (there has been crying, screaming, and a couple of "your mean" directed at me, but its making a difference) but they are getting better, and thats all I was hoping for. It's a simple system, and it can be modified however best suits your family. we started at a smaller amount just in case they did super great, we want to be able to afford to keep this up :) but also becuase we didnt want it to be just about the money.....anyway, here are a few pictures from the first week that we did it, so far its helping behavior, and thats all I was hoping for :)

These are the jars. The flower on in the middle is athenas, the one on the right with a car on it is calebs and the one on the far left is the "lost" jar. where the dimes go when they are lost.