Hi Sue.
The part you need is the 'Bill Holder'. It is important that you do not lose the spring attached to it, otherwise you will need to order this as well. The Bill Holder is only the plastic piece. You will need to ring a Casio dealer in your area, and order it. NOTE: If it is an original Casio drawer, it will normally have a number starting with 'DL-' on the drawer itself (not on the register). They may need this drawer number. Look in the yellow pages, and in most countries, you will find the brand names under Cash Registers. Ring anyone near you who has a Casio logo, and you should be able to get them. Otherwise, just ring a few dealers and ask if they have Casio parts. They will usually know who the agent is, if they have been in the biz for a while, so a helpful dealer will give you their number. They are usually only a few dollars each, and it pays to get a spare one since they are cheap.
Hope this helps,
Mark, July 2008