Police say that at around 4.20pm yesterday four men, one of whom was armed with a hammer, entered a shop on Scotch Street and demanded money from a staff member working at a till.
The staff member managed to get away from the till and alert a colleague while one of the robbers proceeded to hit the till with the hammer.
The robbers then fled the premises empty-handed.
Detectives at Dungannon CID are asking witnesses or anyone with information that could assist the investigation to get in touch with them.
They are especially keen to hear from anyone who may have noticed any suspicious vehicles in the Scotch Street area at around the time of the robbery.
The number to call is the non-emergency number 101.