The trial of Sibongile Mapuranga began in the Summary Court on Wednesday morning.
The court heard how Ms Mapuranga had abused her position as a customer services assistant at the West Store by serving her sister and then cancelling the transaction.
The Justices of the Peace found Ms Mapuranga guilty and she was ordered to pay a £90 fine, £133.10 in compensation to FIC and also ordered to pay court costs of £200.