CVS App Coupon Question

The apps you get on CVS apps vary I'm sure, but every week I get things like $2 off $8 of coffee, $2 off $8 of cereal, $2 off $8 off Gold Emblem nuts, which I take advantage of when combining with manufacturer's coupons, Ibotta, and store sales!

Just a question on the $8 though... is that before the store sale? Like Dunkin Donuts coffee is $9 regularly or something but on sale for $4.99. Would the $2 off coupon work in that case? Or must I buy 2 to total $9.98?

Another thing is because I bought four cereals for $1.99 each and were on sale from originally $5.96 (why is cereal so expensive! I never buy at full price), so it came out to $7.96 at the cash register, but I still got the $2 off even if it didn't reach $8. I'm guessing because the discount came from the original retail price, not the sale price.

If anyone could clarify, that would be great! Would save me from buying surplus just to use a coupon.