I used to work at TRU and I don't know how badly handled rain checks were in other parts of the store,but I worked in the R Zone(electronics) and rain checks were a joke,mainaly because we had no idea what they would send us every day. We couldn't order a specific game,nor could we request one.
I used to keep a note book with customer requests and I would personally follow through with things,but as far as I knew,I was the only person in the department to do this.
My recommendation is that if you are really set on buying a certain game is to buy it online...it's easier to find and you won't have to hassle with a store.