Every time someone pays 11.99 for a cheap generic at walgreens, that's probably 1000% profit considering the 1000 count bottle probably cost 2.50. Money is in the generic drugs, which is why the chains have been freaking out that the prices of generics have been going up the last few years.
That's why the chains are starting to invest heavily in wholesalers, so they have a large buying group and can buy generics for a huge discount. Last I checked, my state Medicaid reimbursement was AWP-17% +0.05 cents. If I'm getting the drug for considerably lower than AWP, I'm still turning a profit. Not every insurance uses this, some use MAC or some other mysterious numbers behind the curtain. Regardless, chain employees will never know the details of an insurance contact and will be kept in the dark. If a store wasn't making money, they would close it (Walgreens recently closed a couple stores because they weren't turning a high enough profit). There's no way that a store that does 1800/week wasn't making a profit.