I tried to take about 8 bottles (maybe some hard liquor too?) with me last winter and the duty is more than you want to think about. I had thought it was 10% but it was way more. I can't remember exactly how much, but really a lot--so much that I preferred to dump the bottles.
When they asked, I told them I was taking them up for an American friend who has a condo in Canada. I think the right answer would have been "I'm taking them to consume myself during my trip." I'm not completely sure whether that solves everything, but I had the impression it would have been better. The other correct answer would have been "no officer, I only have two bottles with me." I also had the impression he wished I had just said that. However, I'm the world's worst liar . . .. The same friend who has the condo told me he lied once and got busted--I can't remember the consequences.
The officer took pity on us and only made us sacrifice one or two bottles, and we paid no duty. That might not happen at a really busy crossing? I would have dumped whatever he told us, because it seemed like the duty was more than the wine was worth. He told us to take them out in the woods near the building, on the Canadian side (we were at a remote low-traffic point of entry) and pour them out. I didn't have a corkscrew so had to break them, lol. He obviously wasn't looking and didn't really care--just told us to dump and continue with our journey. He didn't really want the hassle of trying to figure out the duty.
Next time I'm limiting myself to the approved amounts.