假如你是国内某银行的全币种V家卡,通常用V家汇率的美元记录再按照当日国内某银行美元汇率转成人民币。
银联汇率http://en.unionpay.com/front_ExchangeRate.html
V家汇率http://usa.visa.com/personal/card-benefits/travel/exchange-rate-calculator.jsp
M家汇率https://www.mastercard.com/global/currencyconversion/index.html