Consumers, shippers and small businesses at home and abroad are in flux as an exemption that allowed low-cost goods to enter the United States duty-free came to an end.For nearly a century, the de minimis rule allowed merchandise worth $800 or less to bypass import tax. But it expired at 12:01 a.m. Friday, meaning such shipments are now subject to an additional 10 to 50 percent levy that coincides with the tariff rate of the country of origin, or a flat rate of $80 to $200, depending on which op...