The marks you get in the ATPL exams do not appear in your licence, or on any other documentation that prospective employers get to see. If you are on an employment-linked course (CTC or similar), there may be competitive pressure to get the highest marks in your group and there may be some implied pressure from the school to get high marks, but in reality the airlines are interested in the fact that you have the licence and little more.
That's not to say that you shouldn't try your hardest to do the best you can, but it's emphatically not a disaster if you get 80% instead of 95%.
Scroggs