Interest rates on short-term Treasury securities climbed back to levels in effect earlier this month. The Treasury Department sold $7.6 billion in three-month bills at an average discount rate of 7.04%, up from 7.02% last week. Another $7.6 billion was sold in six-month bills at an average discount rate of 7.07%, up from 7.05% last week. The three-month rate was the highest since 7.05% on Dec. 12 while the six-month rate was the highest since 7.26% on Dec. 2. The new discount rates understate the actual return to investors--7.27% for three-month bills and 7.43% for six-month bills.