When I was that age, ashamed as I am to say it, I use to steal money from my mum's purse. This was quite simply for the reason that I didn't get pocket money and all of my friends did. They were out buying stuff themselves and I didn't have any money to do the same as them.
When I was caught by mum and I told her why I had done it, she couldn't understand it because as she said to me I had never wanted for anything. But what I really wanted was to be able to have my own money and buy myself things - wanted a bit of independence.
I think what stopped me was her saying she would call the police - as a 10 year old I was frightened to death that I would go to prison - but that WAS back in about 1981/82 and I don't think 10 year olds were as clued up then as they are now (I know I wasn't!).
Like SPUDQUEEN and ANDY have said, I agree, you need to find out why this is happening before you can put a stop to it.