On January 1st, 2012 (12:00 am EST), the Province of Quebec will be raising their QST rate from 8.5% to 9.5%. 

1. Go to the Sales Tax menu and click Manage Sales Tax.
2. Click Change Tax Setup.
3. Select Change the rate (% or amount) of an existing tax and follow the onscreen instructions.

Or

1. Go to the Lists menu and click Item List.
2.  Change the tax item for sales
3. Double-click the tax item for sales (e.g., QST on Sales).
4. In the Tax Rate (%) or Amt. field, enter the new rate (e.g., 9.5%) for QST Click OK.
    
5. Change the corresponding tax item for purchases
   1. Double-click the corresponding sales tax item for purchases (e.g., QST (ITC)). NOTE: There may not be a tax for purchases if this is a tax you added yourself.
   2. In the Tax Rate (%) or Amt. field, enter the new rate (e.g., 9.5%).
   3. Click OK.

Once you've changed an individual tax item, any sales tax group item that includes it will also use the new rate.