Looks like a case where you should contact the department of labor (DOL). Your check stub is showing 40 hours, which is good, but if you're being paid your overtime wage in cash, and at a lower rate than you should be (which is $10.87/hr), it seems like your manager is paying you "off the books" as the saying goes. That is to say, he's avoiding making those hours official and thus finding a way to pay you less than he should be, and this is definitely illegal.
As I said, you should contact DOL. Their website is located here: http://www.dol.gov/ and you can just hover over Contact Us for the right contact info.