First, create a new column in the Grade Center using the Add Grade Column button.
Set the "Points Possible" value to zero points. This will insure that anyone who does not get points for Extra Credit does not have it count against their grade.
This will be the column in which to enter points for extra credit to be added to the Total of all points earned.Part Two:
Click on the Action Button (the double-downward pointing arrows) on the existing Total column. Choose "Modify Column" to edit the criteria.
Scroll down to 3: Select Columns, and find Include in Total. Choose "Selected Grade Columns, Calculated Columns and Categories."
Under "Columns to Select," highlight ALL of the columns listed (you may select all by holding down the Shift key and clicking the last column) including the Extra Credit column you created previously. DO NOT include any Calculated Columns (Weighted Total, Average, etc).
Click the triangle-in-a-circle arrow between "Columns to Select" and "Selected Columns" to move the highlighted columns over to selected columns. This will make certain that ALL columns are used in the Total calculation.
Under that section, choose "No" for "Calculate as a Running Total." Having "Yes" selected will ignore any columns with zero "Points Possible" including Extra Credit, so make sure that it is not enabled.
Click Submit. The Total column will now reflect the total of all columns, including the Extra Credit.