topcashback.com appears to offer 10% for Walgreens "Home Medical Supplies & Equipment", approximately enough to cover sales tax in even the worst US tax districts.

However, topcashback has a lot of negative reviews on cashbackholic.com, and I don't think I'd ever seen their name before a few minutes ago. So, I certainly can't vouch for them. Also, be aware that many of these cash back sites have very inconvenient rules for paying out. They may take 90 days to pay, require a minimum balance, insist on paying by paypal, etc.