adding data with duplicate rows

hi there, here's my problem. i have the following rows below, and i need to add the sales data on column d, but i have duplicate rows for the same transaction. for example, rows 1 and 2 are the same, same check number and same date and time, same check total, but there's an entry of how much was paid (20), and another entry of how much is the change (20-10=10). i have 400 transactions with the same case. how will i eliminate the duplicates here?

thank you.

column a is check number, col b is date, col c is time, dol d is check total, column e is tender
A B C D E
CHECK NUMBER DATE TIME CHECK TOTAL TENDER
19 03/01/12 2:00 10 20
19 03/01/12 2:00 10 -10
20 03/01/12 2:05 15 20
20 03/01/12 2:05 15 -5

Oh my God, this is my first post and the reply I got worked!!! Thank you so much Marvinp!

@jppaj22

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