I can confirm this still occurs with Alpha 8.

I have GST (6%), HST (14%), PST (8%) set up in admin/store/settings/taxes.

I've added an action for each of the taxes to admin/build/workflow-ng:
Zones: AB, BC, MB, NT, NU, ON, PE, QC, SK, YT -> Apply GST
Zones: ON -> Apply PST
Zones: NB, NL, NS -> Apply HST

If I set the province to Alberta it will correctly show GST in the payment section, however if I change it to Newfoundland it will now show both GST and HST when it should only show HST.

The correct taxes are shown by the time you get to the review stage.