Families are socking away more money in 529 college savings plans than ever, investing a record $253 billion last year in preparation for the sky-high cost of higher education, according to a report released Tuesday by the College Savings Plans Network. The advantage to 529 plans — named for a section of the U.S. tax code — is that families can invest through such accounts without the earnings being taxed, so long as the funds ultimately are used to pay for college expenses. Earnings on the investments typically are free from federal and state taxes, and grandparents, aunts, uncles and anyone else can contribute to the accounts.