U.S. retail sales increased more than expected in March as the war with Iran boosted gasoline prices and led to a record surge in receipts at service stations, while tax refunds underpinned spending elsewhere. Though higher prices largely accounted for the biggest gain in sales in a year, the report from the Commerce Department on Tuesday prompted economists to upgrade their economic growth estimates for the first quarter. The U.S.-Israel war with Iran is, however, casting a shadow over the economic outlook.