I don't cheat at UBC... The only thing I have cheated on are the little problems worth 0.25% of your mark, and I think I learn better that way. Then again, my average is in the 60's so maybe I should cheat (kidding).
.... "I don't do A. I only do A a little bit when it has little effect..."
If this had been a test and he had cheated in some way it would be a different story, but generally speaking take home exams are a bit of a joke, especially if they are not essay's. I am under the opinion that the only take home exams should be essays, and complex problems (ie problems that require many hours of work, like many programming assignments).
Also PS. If you are seriously worried about your average, most graduate schools in Canada are only/mainly concerned with your upper year (300 and 400 level) courses.
I know for Math/Mathematical finance that none of the graduate schools I have looked at have CGPA requirements other then really low ones like 2.0-2.5, just make sure your GPA on major courses and your last four semester is good (assuming graduate school is a goal).