A pair of chainwide cash register crashes at Target Corp. in June, right around the heavy-sales Father’s Day weekend, may have cost the national retailer $50 million to $100 million in lost sales, according to some analysts. The problems — one of which the company blamed on a “technology glitch,” while another was traced to a tech center run by NCR Corp. — were quickly corrected, but they also point to a deeper issue, said some local experts: Technology has helped to boost business productivity, but it’s also exposed companies to a host of challenges.