Holding samples of phony bills up to the ceiling lights in the atrium of Halton Regional Police Service headquarters in Oakville, retailers got an eyeful and earful of advice from Jodie Sales, a senior analyst with the Bank of Canada.

It may only cost the treasury nine cents to produce a $20 bill, but that pressed paper is chock full of security strips, holographs and special intaglio ink to make copying its image a far more difficult endeavour for counterfeiters. It's working, said Sales.

In 2004, $13.1 million in counterfeit bills circulated through Canada. More than 80 per cent were printed through a common inkjet printer.

After new security measures were introduced that year, the number of phonies dropped significantly, to $3.3 million in 2007. The most popular bills replicated are $20 and $10, said Sales.

Bryan Bauer, a security supervisor at Burlington Mall, has certainly come across many counterfeit $100 bills in his time. At Christmastime in 2006, a man carrying several of the brown bills in his wallet took advantage of the busy shopping season, to pass off his phony currency. He purchased several small cost items, such as a submarine sandwich at one shop and a package of gum and cigarettes at others, handing over the $100 bills as payment. That way he received plenty of change in real bills, making a hefty return on his scam.

Savvy merchants reported the suspicious purchases. The bills were verified as fakes at a bank in the mall and police were called. In all, 11 phony 100 bills circulated through the mall that Christmas, said Bauer. The man was eventually charged and convicted on eight counts of fraud.

Hamilton craft store owner Donna Evans hasn't come across any fake bills that she's aware of, but as a rule has long since refused to change $20 bills out of concern they may not be real.

It's a good practice. According to Sales, those who accept counterfeit bills must accept the loss. She advised storeowners who suspect a customer has a phony bill to ask for another one and explain to them why they think it's a counterfeit, and to then call police.

"I'm glad I came here tonight because now I know what to look for and to do, to make sure it's the real deal," said Evans.

These are the telltale signs to look and feel for: ? Touch the 100 per cent cotton paper. Run a thumb over the raised print at the coat of arms and BANK OF CANADA words. If it's glossy, smooth and doesn't have any protrusions, it's not real.