Export your public key:
keybase pgp export > keybase-public.key
Export your private key:
keybase pgp export --secret > keybase-private.key
Export your public key:
keybase pgp export > keybase-public.key
Export your private key:
keybase pgp export --secret > keybase-private.key
Info here is based on a Magento CE 1.6.1 install. Your version may vary. Also, there's lots of conjecture on my part near the end, so DANGER WILL ROBINSON.
Configuration setting is located at
System -> Configuration -> Tax -> Calculation Settings
Label is "Tax Calculation Method Based On"
Possible Settings are