It is very easy to change the keyboard on your SAM4s cash register when you have a keyboard template. You can find SAM4s cash register keyboard template for download, which will allow you to change and re-print when ever you like or just when you make changes. Don't pay a cash register dealer big bucks for a print out and do it yourself.
If you can't find the model you need try printing one from a model that is close and see if it fits. You will be surprised how many keyboards are the same, however in case it does not print then you might be able to alter the template you downloaded.