Hi Bruce,
Best way is to exchange spending cash to JA. Then calculate cost in US @ 120 to 1. Easier than calculating the variable "exchange" rates of the vendors
example: using 5,000 Ja , ....Subtract the last two zeros = 50.00, (that would be 100 to 1), then subtract another 15% or so and you're within a buck or two.
Or just use your phone to calculate.