The Centennial Group in Orange said it sold 655 acres in Fontana for $25.5 million to Lewis Homes of California, realizing a gross profit of $5.4 million . . . Irvine developer Nexus USA is building what it said is Riverside's first major shopping center in eight years, an $18-million project set for completion early next year . . . Gentosi Bros. Contractors in Irvine won five construction projects valued at $8 million at Arcadia Gateway Centre, developed by Stanley Gribble & Associates of Irvine.