It is enjoyable to debate and share knowledge here with friendly people who share that goal. You, on the other hand, seem to have an axe to grind with your consistent unwarranted insults and holier and smarter-than-though delivery. You are part of what's wrong with online discourse, or what passes for it. Lighten up, have some fun, and let's learn shit together. Or perhaps your position (seemingly) is that you have nothing to learn, but only wisdom to dispense and admonishment for any who might question, and "sorry I don't have time to give you source." It's sad I feel compelled to dismiss you in this way, especially since, after some digging, I did find sources confirming your claim (although it was Ontario or Quebec mentioned in article) that the shops are given leeway of +-10%, exactly as you said. Some people find it fun to walk all over people using the little info they have on a particular subject as their boots. I used to as well, in the earlier days of social media. It seemed the natural way of online conversation. Then I realized I was just being an asshole. Have a great day.