Tax to be excluded in Canada

Hi,

I have a below requirement for Canada customer who is going to have new tax rates from  Jan-2013.

1) Currently we have a setup like compounding tax is getting calculated on QST(Ii.e. say line_amt*tax_rate=10*5=0.05---GST and QST= 10.05*9%= so finally tax_amt= GST+QST))

2)Now from Jan-2013 we need to only QST to be calculated excluding GST calculation.

How can this be acheived.

I tried using below steps but the results were not fruitful

i)Created new tax rule  by unchecking "Allow Compounding" and by end dating old tax rule.

ii)Created new tax rate effective from Jan-2013. and end dated old tax rate.Still GST is getting fired  but now its not compounding.