Code:
bash-2.05$ cat mar.txt
,,,,,6630140,XXXXXXXXXXXXXXX, 0020.00,USA
,,,,,6630150,XXXXXXXXXXXXXXXL (xyz, 0010.00,USA
,,,,,6630150,XXXXXXXXXXXXXXX(xyz), 1300.00,USA
bash-2.05$
bash-2.05$
bash-2.05$ nawk -F, '$8=sprintf("%.2f", $8)' OFS=, mar.txt
,,,,,6630140,XXXXXXXXXXXXXXX,20.00,USA
,,,,,6630150,XXXXXXXXXXXXXXXL (xyz,10.00,USA
,,,,,6630150,XXXXXXXXXXXXXXX(xyz),1300.00,USA