How to deal with extra points in exams? If a midterm exam was from 100 points with 5 points bonus(extra points). Then should the total grade be out of 100 or 105? How to deal with cases of students getting above 100? Should their points be used as bonus for the next exams or just throw them out since they don't need them? I feel that since some students would benefit of the 5 points, those who were above 100 should also do, but I am not sure how?
When I have dealt with extra credit in the past, it was simply retained in the records until the very final accounting of scores at the end of the course.  Thus, if the exam was out of 100 points, it was still considered to be out of 100 points, and some people simply had more than the maximum possible.

When grades were combined together in the final accounting at the end of the course, having a score above the maximum effectively ended up helping compensate for lower scores on other tests (though perhaps not one-to-one, depending on relative weighting).  If a particularly amazing student turned out to get more than the maximum in the class overall, then it wouldn't affect anybody at all: the curve wasn't shifted and they simply got top marks, as they would have if they'd gotten the maximum.