That is deceiving, however I think that since McMaster states that it must be before 5pm, then that is the time you have to cancel by. They are probably referring to the end of the "work day," meaning most offices are open 8:30/9:00-5:00. Just cancel it by 5 anyway. I know you want to see your midterm grade before you cancel it, but in reality you're not going to get that grade for a few more days anyway. If you're still unsure, contact the Office of the Registrar.
__________________
|