Since you mention Rs as Currency, should we presume that you are talking of Payroll for India?
Please check the Wiki page for Payroll of your Country.
Payroll Spaces - ERP Human Capital Management - SCN Wiki
Did you try to do a Payroll Simulation with the "Display log" box checked, in order to drill down into that log into the Taxation Sub-schema? You should be able to see the details of the Tax Calculation.