Based this forum http://moodle.org/mod/forum/discuss.php?d=133034 and testing it appears there is no current way to accomplish all the following simultaneously:
1. Display correct number of points (reall) earned by student to date
2. Display correct number of points (real) possible to date
3. Display correct percent earned by student to date
4. Include selected items for extra credit
5. Calculate items as NULL rather than zero for those items which the student has not attempted
6. Group items based on teacher preference (some want grouped by unit or chapter, others want by semester, or some other combination)
7. All while avoiding using "graded" and "to be graded" categories to correctly calculate items as described here: http://docs.moodle.org/en/Grades_FAQ#How_can_I_grade_some_of_my_activities_without_the_results_affecting_my_students.27_course_total.3F