First, go to Preferences->Accounts and provide your UPS Sales Representative with the "UPS Rate Code."
Your UPS Representative will then enable negotiated rates. Once this is complete, you need to select the "Both Published and Negotiated Rates" Rates option.
When integrated with FileMaker Pro, you can access the returned rates by accessing the fields below:
Response_TransportationCharges - Published UPS Rate
Response_NegotiatedRates_NetSummaryCharge_GrandTotal_MonetaryValue - Discounted UPS Rate
Note that you will receive a warning message when shipping if you select the "Both Published and Negotiated Rates" option before it is enabled by UPS.