I have a transaction of $100, I want to add two taxes tax1 10% and tax2 10% to this transaction. Now the openERP giving total $120. Tax1 10% on $100 is $10, tax2 10% on $100 is $10, so total is $120. But my scenario is different here. I want to add 10% of tax2 on $110. I.e. base=$100, apply tax1 10% total $110, after this apply tax2 10% on (base+tax1) $110, so now tax2 10% value=$11, total of transaction is $121.I have tried with childrev taxes, it's taking parent tax value as base. For example i have created a child tax 10% for parent tax 10%, transaction total=100. When i select parent tax as a tax in this transaction, it' s considering two taxes but the values are different parent tax value=10 child tax value=1. i.e. child tax is the tax on parent tax.... . Is it possibel in openerp to get total $121 ?. Please can any one suggest me a way to get this.