The man entered Bargain Booze on Station Road just after 9pm on Monday (August 11) - he was carrying a knife and demanded the money from staff.
He stole the till and was last seen running down John Street.
He is described as white, in his late 20s, of slim build, around 5ft 7ins to 5ft 8ins tall and he spoke with a local accent.
He was wearing a light grey hooded top with the hood up, navy blue jogging bottoms and a black scarf around the lower half of his face and nose.
Witnesses or anyone with information is asked to call South Yorkshire Police on 101 quoting incident number 1024 of 11/8/14.
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