Three masked men held up Co-op Travel in Crosspool on Friday night.
At around 5.20pm the robbers, one of them carrying what is believed to be a shotgun, burst into the shop and threatened staff. Thankfully, no-one was hurt during the incident, but staff were left very shaken by their ordeal.
Witnesses say the robbers left the scene with currency of different denominations, leaving a trail of bank notes in the precinct.
They made their escape in a white Seat getaway car, which was later torched on Rivelin Park Drive.
Police cordoned off the area around the shop until around 8.30pm on Friday night. Detectives investigating the robbery want to hear from anyone who has any information, and urge them to come forward and contact South Yorkshire Police on 101 quoting incident number 942 of 24 February 2012, or call Crimestoppers anonymously on 0800 555 111.
The incident in Crosspool follows a similar robbery in Bradway at another branch of Co-op Travel last December.