The latest sales tax increase in Los Angeles County took effect Thursday after voters approved a half-cent hike in June to support health care and other essential services. The Essential Services Restoration Act, known as Measure ER, increased the county's baseline sales tax rate from 9.75% to 10.25%. The increase is temporary. Measure ER allows the tax to remain in effect through Oct. 1, 2031, and is projected to generate about $1 billion annually. Sales tax exemptions include groceries, prescription medications, and medical equipment.