Tax rates not being updated when going back and forth in the checkout steps

[jennbrewer]

Issue with tax rates not being updated when going back and forth in the checkout steps as below:

1. Complete step one and proceed to shipping step
2. Click the Previous step button and update the province.
3. Proceed to shipping step but taxes aren't updated.
4. Click the previous step button and then proceed to shipping step again - now taxes are updated for the new province.

Notify customer once fixed:
https://app.intercom.io/a/apps/7236196445273cea007287c0c90a2f0d598567cc/inbox/inbox/1503786/conversations/14508345346