How to sum entries in a internal table

Hi Experts,

Below is the data which is there in my internal table.

BUKRS BELNR GJAHR TXGRP HWSTE 1000 5100000135 2014 1 4000 1000 5100000135 2014 1 3000 1000 5100000135 2014 2 8000 1000 5100000135 2014 2 6000 1000 5100000135 2014 3 12000 1000 5100000135 2014 3 9000

My requirement is to sum the data when the TXGRP field is repeating and the internal table should store only one entry if multiple entries found against a unique combination along with the sum of the field HWSTE.

Below is the to be data.

BUKRS BELNR GJAHR TXGRP HWSTE 1000 5100000135 2014 1 7000 1000 5100000135 2014 2 14000 1000 5100000135 2014 3 21000

Please guide me to achieve this.

Thanks & Regards,

Naveen.