Looking for cgi/java applet - Looking to do simple currancy conversion

I have a client who wants to use a specific shopping cart program. We have it setup and running, with the prices in american dollars. This client is also hoping that some of his local customers can hop onto the net at any hour of the night and order things, for this reason we wants Canadian prices to be easily accessible.

I suppose the easiest way would be to provide a small input box into which you can enter any amount in american dollars (ie, the subtotal or total that the shopping cart gives you) and it will spit out the converstion on Canadian dollars. Does anyone know of a simple currency converstion program?