Shortly before closing time, two men threatened staff in Strawberry Fields on Great Western Road before stealing clothes.
They then made off in a silver saloon car along Great Western Road, before turning into Belmont Street.
Neither of the two staff members were injured in the robbery but both were said to have been left very distressed.
Police are now appealing for information about the incident, on Wednesday at 4.50pm, which left the shop closed for a day.
Both suspects are described as male, with local accents. Both are around 5ft 10in tall while one was said to be stocky and the other slim.