Need help summing values in multiple rows between two dates.

[mwilkinson11]

I have the below table.  I would like to sum all the rows in column C (TIME GAP MINUTES) between each SHIFT_START_TIME (Column D) and group by shift start time.  The dates can sometimes span over 2 different calendar dates if a user is working night shift.  

I have tried using the Peek and Previous functions with no luck. Does anyone have a good solution to cumulating values?

I appreciate any help/insight. TY!