How long does oxycodone stay in system?

I took a drug test for my job after 16 days of taking roxicodone 30s and FAILED for opiates. I was taking 3, 30 mg tabs a day for two weeks and nothing else. 16 days after the last pill, I took a urine test and failed. Therefor, everyone is different as I ahave heard that people have tested clean after only five days. DON'T BET ON IT! Give yourself a month as far as I am concerned to make sure.