def tax_codes
      @tax_codes ||= begin
        response = TaxCloud.client.request :get_ti_cs_by_group, tic_group: group_id
        tax_codes = TaxCloud::Responses::TaxCodesByGroup.parse response
        Hash[tax_codes.map { |tic| [tic.ticid, tic] }]
      end
    end
def tax_codes
      @tax_codes ||= begin
        response = TaxCloud.client.request :get_ti_cs_by_group, tic_group: group_id
        tax_codes = TaxCloud::Responses::TaxCodesByGroup.parse response
        Hash[tax_codes.map { |tic| [tic.ticid, tic] }]
      end
    end
All Tax Codes in this group.