[cperciva]

charge based on residence

Duh, you're right of course. I know this, too -- I have to go through the same headache of charging different rates to my Canadian customers based on where they're located.

I must have been asleep when I wrote that comment... alas, it's too late to edit it now.

I pay 5% GST - there is no HST/PST in Alberta. But I pay this 5% GST on droplets that are in the NYC and SFO datacenters.

Right, if the service is being provided to you by a Canadian company then they have to charge GST regardless of where the servers are. The same goes for Tarsnap -- my servers are EC2 instances in the US, but I remit GST/HST for my Canadian customers.