Vtiger product tax change

Create a New tax percentage from VTiger CRM

CRM Setting -----> Other Setting---> Tax Calculation ----->Add New Tax

Log into mysql database;
mysql -u root -p

Vtiger Tax table

select *from vtiger_inventorytaxinfo

// Find you tax table and tax class id and percentage

Product tax master table 

Select *from vtiger_producttaxrel where taxid ='your Tax id'

Update Quary  vtiger_producttaxrel

UPDATE `vtiger_producttaxrel` SET `taxid`='your new taxid' ,`taxpercentage`= 'tax percentage'