There are at least four interest rates associated with Treasury bill issues: 1  The Average Tender Rate refers to the average of all accepted bids, i.e. the actual amount paid for each $100 Treasury bill. 2  The Average Discount Rate is determined by subtracting the average tender rate from 100 and multiplying by 4. The Market Rate is the rate the Central Bank charges on Treasury bills purchased from its portfolio. It is determined as the Average Discount Rate, less 0.1%.