Changing Tax Parameters to reflect Canada's new HST

We have, I-Don't-Know-How-Many, forms and reports, all of which use GST (Goods and Services Tax) and PST (Provincial Sales Tax) to come to a cost total for invoicing, POs and Quotes in Contract Manager 12.5.

Now with the Harmonized Sales tax coming in - i have to change all these forms to reflect the 13% sales tax instead of the GST and PST combined.

I have to admit - i'm a total newcomer to Primavera.  I started at this job last February, and before then, i'd never even heard of this product, so i'm completely in the dark.

Does anyone have any ideas how they would go about doing this?