You still may be entitled to overtime pay:

• Some workers get paid per job.  For example, delivery boys often get paid $10 for every delivery they make.  Technicians or installers often get paid $25 for every receiver they install.   

To figure out the overtime rate, you must first calculate the ‘regular rate of pay’.  To do so, we look at how much the worker receives in total compensation each week and how many hours each week he works.   

Example:

Tom installs satellite tv systems.  He  is paid $20 for every receiver he installs.  One week, Tom works 60 hours and receives a total of $600 for the receivers he installs.  Tom's regular pay rate is $10/hr, therefore his OT rate is $15/hr.