Hello:

For those of us still confused about assigning tax rates etc. here's a blow by blow on how to adjust your existing settings.

My clients are in BC so BC PST is used. Please adjust for your province.

Locations/Taxes --> Tax Rates
Delete
GST/HST/PST Class Zone: BC PST
GST on Shipping Zone: BC PST

Locations/Taxes --> Zones Definitions
choose Canada GST Zone, click details
Delete BC and ON
Click BACK to go up one level.

choose PST Zone, click details
delete BC
Click BACK to go up one level.
delete PST Zone

Choose HST Zone, click details
Click INSERT to create new sub-zone:
- Country: Canada; Zone: Ontario
Click BACK to go up one level.

Create the HST Zone for BC
- Zone Name: BC HST Zone
- HST (only when shipping to BC)

Now choose on the newly created "BC HST Zone", click details
Click INSERT to create a new sub-zones:
- Country: Canada; Zone: BC

Locations/Taxes --> Tax Rates
create TWO Tax Rates:

- Tax Class Title: GST/PST/HST Class
- Zone: BC HST Zone
- Tax Rate (%): 12.0000
- Description: 12.0% GST#99999 99999 RT0001
- Priority: 1

- Tax Class Title: GST Shipping Class
- Zone: BC HST Zone
- Tax Rate (%): 12.0000
- Description: 12.0% GST on shipping
- Priority: 1

I don't think that completed order are changed, so any paper trail should still exist. I hope I've covered everything. If I've missed anything, do let me know.