Their question was - after having a recent robbery just nearby - what can she do, given that avoidance is not a likely strategy when you have to be behind the counter to serve customers. The robber in question was a physical monster and she's quite petite. Her main concern wasn't the robbery, as she knows to give up the money, but rather being dragged into the back of the store and raped.
As I mentioned to them life is about choices and consequences (at least it should be) and if you choose to work in one of the most dangerous professions in the country then you place yourself in harms way. First defense therefore would be, do I really need the job that badly given the potential risks? What about a job at Target, or the local grocery store stacking shelves? How about one at a call center answering phones at night?
If you do have to be there and the concern is physical violence then you're going to have to learn how to fight. Whether that's with a gun or bare hands depends on a lot of variables including whether or not store policy permits clerks to go armed for example.
Finally, some other solutions were offered. How about secreting a weapon in the store room that you're concerned about being dragged into? What about acqiescing and walking ahead of the guy and then running at the last second and barricading yourself in, or setting up a shelf to pull down to jam the door and buy you enough time to escape out the back, through a skylight etc. Is your cell phone back there so you can call for help while you're barricaded?
That's about all one can do in that situation but given the inherent risk I'd be looking for a safer occupation.
Here by the way, is a quote regarding dangerous jobs. Note how many convenience store clerks are shot every year.
Homicide was the second leading cause of job-related deaths, accounting for 16 percent of the total. Robbery was the primary motive for workplace homicide. About half of the victims worked in retail establishments, such as grocery stores, restaurants and bars, where cash is readily available. (31,000 convenience store clerks are shot every year.)