I would like to add an auto sum in my macro. This is my issue:

when my macro finishes, on column B, I would like to have to total up b2 to whatever is the last cell that contains the value in column B. If the last value ends in B10, I would like B12 to have the total. If the last value ends in B13, I would like B15 to have the total. Please help. Thank you.