London Drugs

London Drugs, which is only located in western Canada is the only store in Canada that allows coupon stacking. What this means is that they allow you to use more than one coupon per item, up to the full value of the item. As long as each coupon is different, not expired and the total does not exceed the price.
I have been able to get almost free or free shampoo, cleaning products, juice, personal products, pain relief, groceries (limited selection) dog food, and cat food. You do have to pay any tax still.
Another great store is Superstore in western canada. They have Instore coupons and allow you to use one instore coupon and one manufacture coupon per item. This is their policy. So you can end up getting items for almost free, sometimes free. Sometimes the cashiers do not know about this policy and will tell you that you can only use one coupon. Funny how the consumer is more trained than their cashiers!