If you don't work for yourself (and can therefore make your own rules regarding firearms), then the best thing you can do is to hand the junk over. It isn't yours, it isn't your money. No point in engaging in violence over something that isn't yours. Drawing your own gun isn't a magic end to the robbery and can easily be what takes the robber's own threat and turn it into action on his part. Not a worthwhile gamble for something that isn't yours.
Yeah, except that, statistically, you're more likely to come out unscathed if you resist with force, per Kleck.
Gary Kleck, Targeting Guns: Firearms and Their Control, Walter de Gruyter, Inc., New York, 1997.