The total assessed value of property in California rose 10% last year as county rolls broke the $1-trillion mark for the first time, the state Board of Equalization reported. County assessment rolls increased in the 1987-88 tax year by $103 billion, or 10.4%, to a statewide total of $1.0977 trillion, the tax board said. The total assessment of the state rose by 10% from last year's $1.0587 trillion to this year's $1.1651 trillion. Inyo County led all others with an increase of 18.8%, barely beating Tuolumne County's 18.5% growth rate. State tax officials said Inyo's dramatic increase was fueled by geothermal energy development, while Tuolumne's was because of gold mining. Los Angeles County assessment grew 11.4% to $321.1 billion.