Hello Mike
We find that if you set your weightings to reflect your percentages, then the totals are usually accurate. Alternately, find your lowest denominator and use that for your weightings:
Quizzes = 20% of the final grade - 2 weight - twice the lowest value
Assignments = 10% of the final grade - 1 weight - lowest value; everything else becomes a factor
Project = 25% of the final grade - 2.5 weight - two and a half more than the lowest value
Exams = 40% of the final grade. - 4 weight - four times the lowest value
Note, you can also use half values; example 5% might translate in this instance to a weight of .5
Hope this helps,
Susan