我们使用快速结账，并希望根据结账时在PayPal上选择的送货地址计算税金。我们可以增加订单总额来计算税金，但税额总是记为零。这是我们的流程：
我们SetExpressCheckout的订单总数为PAYMENTREQUEST_0_AMT，PAYMENTREQUEST_0_TAXAMT为零（或省略），订单总额为MAXAMT +最高可能税。
在回调时，我们会运行GetExpressCheckoutDetails来查找送货地址。
如果有税，我们将DoExpressCheckoutPayment与PAYMENTREQUEST_0_AMT一起（订单总额+税金），PAYMENTREQUEST_0_TAXAMT和L_PAYMENTREQUEST_0_TAXAMT0作为税。
总订单按金额（订单总额+税金）处理，但返回的PAYMENTINFO_0_TAXAMT仍然始终为零。
是否需要传递额外的字段才能正确应用税？
设定：
METHOD: "SetExpressCheckout"
PAYMENTREQUEST_0_PAYMENTACTION: "SALE"
PAYMENTREQUEST_0_AMT: 1.00
PAYMENTREQUEST_0_ITEMAMT: 1.00
PAYMENTREQUEST_0_SHIPPINGAMT: 0
MAXAMT: 1.1
L_PAYMENTREQUEST_0_QTY0: 1
L_PAYMENTREQUEST_0_AMT0: 1.0
捕获：
METHOD: "DoExpressCheckoutPayment"
PAYMENTREQUEST_0_PAYMENTACTION: "SALE"
PAYMENTREQUEST_0_AMT: 1.1
PAYMENTREQUEST_0_ITEMAMT: 1.1
PAYMENTREQUEST_0_TAXAMT: 0.1
PAYMENTREQUEST_0_SHIPPINGAMT: 0
L_PAYMENTREQUEST_0_TAXAMT0: 0.1
L_PAYMENTREQUEST_0_AMT0: 1.0
结果：
ACK: "Success"
VERSION: "95"
BUILD: "7161310"
PAYMENTINFO_0_TRANSACTIONTYPE: "cart"
PAYMENTINFO_0_PAYMENTTYPE: "instant"
PAYMENTINFO_0_AMT: "1.10"
PAYMENTINFO_0_FEEAMT: "0.33"
PAYMENTINFO_0_TAXAMT: "0.00"
PAYMENTINFO_0_PAYMENTSTATUS: "Completed"