The discounts were not enough for 12 people who were arrested for suspected shop theft and cheating, over the first four days of the John Little Mega Expo Sale.
A police statement on Monday night said that seven men and five women, aged between 17 and 60, were nabbed between last Thursday and Sunday.
They were involved in six unrelated cases of shop theft and two cases of cheating at the 11-day department store sale held at the Singapore Expo.
Items stolen included clothing, footwear and other household items, while in the cheating cases, the suspects are said to have switched the price tags of items to those of lower prices before payment was made at the counters.
In the statement, the police also warn that shop theft and cheating are serious crimes.
The statement added: "The event organisers have taken measures against theft and cheating by deploying security personnel and plain-clothes in-house detectives."
Those convicted of shop theft can be punished with a jail term of up to seven years and a fine. Cheating carries a maximum sentence of 10 years in jail and a fine.
The John Little Mega Expo Sale is on from Nov 14 to Nov 24 at Singapore Expo Hall 5.