Required a function module to capture cst/vat defined for excise invoice

Sir,

          Cst/Vat is defined as 5%. In smart form for excise invoice the amount of cst/vat will be calculated against total of the invoice of 5%.

          Thus there any function module to capture the 5% of cst/vat from komv structure.

           By this i will get the cst/vat when they print the smart form.

Regards.

  Satish.P.