The Secret Service is issuing a warning about counterfeit $100 bills this holiday season that have been hitting retailers in the purse.

Authorities say that many businesses have been targeted by the bogus $100 bills and other forms of counterfeit money because the counterfeiters have found a way to avoid detection by the businesses through 3D printing.

“Sometimes they bleach the $1 bill and they print $5 or $20 on top of that and when you use the pen, it doesn’t work, it shows that its good currency,” said South Philadelphia 7-Eleven store owner Vincent Emmanuel.

Emmanuel’s store recently got burned by scammers who used several thousand dollars of fake bills to purchase prepaid Visas and Mastercards.

“And the clerk behind the counter is always busy. By the time the person realizes that it’s a fake bill, the person is out the door,” said Emmanuel.

The Newport News, Virginia, police also noticed an uptick in counterfeit bills being passed along at retail establishments.

“It is really sad, and I work hard for that money,” nail salon owner Hind Hammoune explained.

The Secret Service estimates that in 2018, more than $100 million in fake money was passed along throughout the U.S.

The agency also shared a few helpful tips to spot fake cash, such as noting a bill’s security features.