Last week, Mayor David Miller announced a 5-cent charge on plastic shopping bags, intended to encourage consumers to bring their own, environmentally-friendly alternatives to carry their groceries. The plan is supposed to reduce Toronto’s plastic bag use by 70 per cent.

It’s common knowledge that a plastic bag takes around 400 years to disintegrate in a landfill. The best way to change a person’s habits is to target their wallet. Individual stores have charged for bags as long as I can remember.

Toronto grocery stores hand out about 460 million shopping bags per year. When you think about those bags sitting in landfills for centuries, it’s clear that the city should take measures to reduce their use. While the bag charge seems reasonable, there’s a catch.

All of the profits will go directly to the stores that sell the bags. If the charge was implemented to help the environment, the revenue should go toward a related cause. Many grocery stores have promised to put the money towards environmental movements, but how can anyone hold them to their statements?

What’s an extra 5 cents? Well, stores still stand to gain a profit, however small—a plastic bag only costs around 1.5 cents. Of course, a 1.5 cent charge is hardly an adequate incentive to bring your own bag, but the 3.5 cent mark up means that stores will gain a 200 per cent profit on each bag they sell, according to the Toronto Star.

Get out there and buy your reusable bags and plastic bins now. You’ll not only be helping the environment, you’ll be making sure that your money doesn’t dribble away from you—5 cents per shopping trip adds up faster than you’d think.