Fake $50 and $100 notes have been used target five businesses in the St Marys, Mount Druitt and Penrith area since June.
St Marys police have called on the community to be wary of counterfeit notes.
Police said those who think they have received counterfeit money should check the note’s security features.
They said to take note of the person who gave it to them and the vehicle they are driving.
Anyone with information should contact Crime Stoppers, 1800 333 000.