The man, armed with a silver handgun, went into the business and demanded money.
The suspect is described as a white man, about 5-foot-4, 150 pounds, clean shaven and wearing a white baseball cap, a light gray hooded sweatshirt and light blue baggy jeans. No age estimate was given.
The suspect also had a tattoo that said "Megan" on the right side of his neck.
Anyone with information should contact Dublin Police Services Investigations Sgt. Yesenia Sanchez at 925-833-6682.