I agree with most of the previous posters that you should do your utmost to achieve the best results you can - but your career is hardly going to stall if you don't get the results you want.
However I think the results may be more important the some posters acknowledge. It may not impress the Chief Pilot much but it's exactly the sort of thing that might impress his secretary or someone in the Human Resources department. It might just be one of the things that helps your CV get plucked from the sea of applications that the airlines receive.
Remember also that many self sponsored people have managed to get jobs through CTC's Wings ATP scheme. The application for this is not on their website at the moment but I'm almost certain that you have to include your ATPL pass rates on it. CTC's own cadets achieve a 91.2% average mark. So if you may not be viewed as favorably as you might like if you scrape through with a 77% average.