More likely, she could get hit with a personal fine if caught selling to underage teens.
Over here, we have "Think 25". I always abide by it, no matter how much a person screams, whines or cries. The legal age is eighteen to buy cigarettes or alcohol, but we have to ID if a person looks under twenty five. If we get caught selling to an underage person, we personally get whacked with a fixed penalty notice which is an £80 fine. If you don't pay it, you go to court. You could also potentially lose your job.
So sorry, but I'm d@mned if I'm taking that risk, ta very muchly.
(Note: Not directed at Hayley, as such, but I get this all the time at work and it does get very irritating)