Examples of configuring currency for different locales and leveraging Rails ActionView::Helpers to format currency.

currency_example.rb

include ActionView::Helpers # If you want to test from a Rails console

number_to_currency(12.34, :locale => :en) # => "$12.34"
number_to_currency(12.34, :locale => :ja) # => "12円"
number_to_currency(12.34, :locale => 'en-GB') # => "£12.34"

en-GB.yml

en-GB:  
  number:
    currency:
      format:
        delimiter: ! ','
        format: ! '%u%n'
        precision: 2
        separator: .
        significant: false
        strip_insignificant_zeros: false
        unit: £

en.yml

en:
  number:
    currency:
      format:
        delimiter: ! ','
        format: ! '%u%n'
        precision: 2
        separator: .
        significant: false
        strip_insignificant_zeros: false
        unit: $

ja.yml

ja:
  number:
    currency:
      format:
        delimiter: ! ','
        format: ! '%n%u'
        precision: 0
        separator: .
        significant: false
        strip_insignificant_zeros: false
        unit: 円