I am in SC category and have 62% in CBSE board PCM and overall, all percentage including best 5 subject is 66% will I get IIT?

It is compulsory to pass in CBSE Class 12 internal assessment. Students will be considered as fail if they don't qualify in internal assessment.

Many CBSE Class 12 follows an 80-mark theory and 20-mark internal assessment pattern. In such cases, students must secure a minimum of 26 marks out of 80 in the theory paper and 7 marks out of 20 in internal assessment.

CBSE may award grace marks in exceptional cases where a student falls short of passing by a small margin. It is given at the discretion of the board. 

The grading system of CBSE Class 12 is given below.

CBSE Class 12 merit certificate in each subject is awarded to the top 0.1 % of
candidates passing that subject. This is subject to passing the exam.