How can I get incentive report from tally?

You can create cost center as per sales man and record the transaction then you can go to GOT>>display>>Statement of Account>>cost center. Here you can check cost center wise or cost categories wise report. Or if you want cost center profit and loss report then you can use a add-on "Cost center wise profit and loss account 1.4" which is given in tally shop. You can try it for 3 days later on you can buy if it is useful for you. Currently we have noted same issue in Tally. Currently we are working on same. Once it will enhance you will get update.