Yes, it is!
Do you want to make sure that your sales rep are entering sales rep info and collecting customer information on every sale? No problem. In the top navigation menu, click the "Settings" link.
On the "Settings" page, click the "POS" tab and you will land on this page:
By default, both of these switches will be set to the "No" position. If you turn these switches to the "Yes" position, as seen below, your sales reps will not be able to complete tickets in the POS without providing a Sales Rep or Customer on the ticket.