An anonymous reader shares a PCWorld report: A new South Dakota law may end up determining whether most U.S. residents are required to pay sales taxes on their Internet purchases. The South Dakota law, passed by the Legislature there in March, requires many out-of-state online and catalog retailers to collect the state's sales tax from customers. The law is shaping up to be a legal test case challenging a 25-year-old U.S. Supreme Court ruling that prohibits states from levying sales taxes on remote purchases. Unless courts overturn the South Dakota law, it will embolden other states to pass similar Internet sales tax rules, critics said. The law could "set the course for enormous tax and administrative burdens on businesses across the country," Steve DelBianco, executive director of e-commerce trade group NetChoice, said in a statement. If dozens of states adopt Internet sales taxes, online sellers could face audits and changing tax rules in thousands of taxing jurisdictions nationwide. Even with software that could make tax calculations easier, that would be a burden, NetChoice says. And online shoppers could end up paying up to 10 percent more for many products.