SASTRA university takes into consideration one's JEE score as well as his marks in the 12th boards, after which they prepare a meritlist of their own based on few criterias which are:

1. First criteria has 70% of seats. In this case, JEE Mains score is given 25% priority and boards marks are given 75% priority.
2. Second criteria is admission on the basis of only marks obtained in the board examination. SInce it has only 30% of seats , one has to secure 95 and above marks in his/her board exams.

So, I would suggest you to check the eligibilty criteria according to your JEE marks and not percentile.