I use the Shaw's rewards system and their digital coupons and I feel like I do pretty well every week. I recommend looking into their app and checking their coupons and the ad where it lists the Fab 5. (The Fab 5 is a system where you get the items for sale as long as you buy any 5 (or more) of the things listed. It's usually pretty easy to do.) You earn reward points as well and the rewards can be exchanged for $X off next purchase depending on how many points you exchange. 12 points = $20 off, for example. Certain items can also be exchanged for the points as well. Idk overall I prefer Shaw's.

That said I used to shop at Walmart for the majority of my groceries and they are cheaper than grocery stores in general. Though with some stuff, not by much. Luckily Walmart and Shaw's are very near each other in Barre/Berlin.