Canadian Sales Taxes

For Canadian operators using Cash Register Express and Nitrosell for your online operation, how or what have you used to track and charge the appropriate sales taxes if you are shipping across Canada? Are you able to set up fields in CRE, so say for instance you are based in Saskatchewan and ship an item to Ontario, that the proper HST rate is charged to the customer, and you are able to keep track at month end? Just trying to see how others have things set up.