I have done this before as follows
Add a column between A and B set B2 to equal "=if(A2="",B1,A2)" Fill down and hide the column.
In what is now E2 (Total) the following formula should work "=SUMIFS(E2:E15,B2:B15,A2,C2:C15,"Adjustment")"
I get the following
Remember to hide column B I hope this helps