The fare has to be quoted in the currency of the country where the itinerary originates, and they have to be sold in the currency of the country where the ticket is purchased.

So a US origin RTW fare has to be quoted in USD. But if you buy it in Canada, you have to pay the fare converted into CAD.

Given the huge discrepancy in RTW's, if you are going to do it regularly, it is best to buy a OW from US to the point of origin (even Canada is a bargain, but Hong Kong, Thailand and India are all attractive), and 'start' the RTW there.

As each one is used, you start a new one to get home.