CVS beginner question: "$10 ExtraBucks Rewards for spending $20 on Colgate Optic White Oral Care or Sensitive Toothpaste"

I'm trying to get started in the wonderful world of ExtraBux and I had a question for you sophisticated people.

I am experimenting this offer on an Optic White toothpaste:

$10 ExtraBucks Rewards for spending $20 on Colgate Optic White Oral Care or Sensitive Toothpaste

I put some qualifying toothpaste in my online checkout cart. The total is over $20 before coupons, but under $20 after coupons. As a result, the offer above does not trigger.

I think I see people getting this offer to trigger in this situation. Is there a trick to make this work? I think maybe I need to go into the store. Would that work?