The latest two incidents were reported on Thursday.
David Compton, owner of Compton's Market, found shattered glass and two handfuls of rocks on the floor -- yet again.
"We're shocked because we don't know why anyone would do this," Compton said.
Compton said vandalism attacks since January have done $20,000 worth of damage.
Nearby, the rock-throwers have also hit other businesses, including a dance studio and a bakery.
Police said vandalism always takes a back seat to crimes in which somebody is hurt.