cc_fees.rb

  def estimate_fee(cents, cardtype)
    case cardtype.to_s.downcase
    when /dankort/
      # Dankort: 
      # http://www.pbs.dk/da/produkter/dankort/Documents/DK_Prisliste_Dankort_eDankort_DK.pdf      
      # Transaction size         Price
      #        0 -  50.00 DKK    0.70 DKK
      #    50.01 - 100.00 DKK    1.10 DKK 
      # > 100.01                 1.45 DKK + 0.1%
      # Using this: 1.45 DKK + 0.10%
      if cents <= 5000
        70
      elsif cents <= 10000
        110
      else
        (145 + 0.001 * cents).round
      end
    when /-dk$/
      # MasterCard-DK, Visa-Electron-DK
      # http://www.pbs.dk/da/produkter/internationale-betalingskort/Documents/IK_Prisliste_MasterCard_Maestro_Visa_VisaElectron_VPAY_JCB_ChinaUnionPay_AmericanExpress_DK.pdf
      # 1.25% (minimum 0.70 DKK)
      [0.0125 * cents, 70].max
    else
      # http://www.pbs.dk/da/produkter/internationale-betalingskort/Documents/IK_Prisliste_MasterCard_Maestro_Visa_VisaElectron_VPAY_JCB_ChinaUnionPay_AmericanExpress_DK.pdf
      # Up to 3.75 % (minimum 1.95 DKK)
      [0.0375 * cents, 195].max
    end
  end