IOWA CITY — Some businesses in an eastern Iowa county are pledging to retain a $10.10 base wage for their employees, despite the Legislature nullifying the local minimum wage boost. The Johnson County Board of Supervisors voted two years ago to use three 90-cent increments to increase the $7.25 minimum wage. The Legislature voided the ordinance in March, saying it was unenforceable. The Iowa City Area Chamber of Commerce surveyed its roughly 900 members after the Legislature’s decision.