The functions ROW() and COLUMN() will give the current cell's row and column. Use them in the ADDRESS() function to create a string representing the range from the top of the current column to the row above the total. Then use the INDIRECT() function to turn that string into a real range to give to the SUM() function. The formula for the total cell would then be:
=SUM(INDIRECT(ADDRESS(1,COLUMN())&":"&ADDRESS(ROW()-1,COLUMN())))
Put that in any cell in a spreadsheet and it will produce the sum of all the numbers in the column above that cell.
