Cashier help?

I’m a front end cashier and we recently got an updated POS system. It looks very similar to the current SCO system. We have several tax exempt customers but every time we try to enter their numbers, the system rejects it and gives an error message. When we send them to customer service it works. They are still running the older system. My co-worker says there is no way to do it at the new registers- I want to make sure before I give up. I came to where I know I can get a definite answer.