In JobRoller you can set the job salary settings from the
JobRoller admin dashboard here, and this could be whatever you need to include (hourly rate, annual salary etc). To clarify though, this is not specific to job types, so they would see all available salary options in the dropdown menu to choose from. If you want to achieve exactly as you describe where the job type is selected first, with only specific salary options to appear, then it would require customization on your part.
AppThemes does not offer customization services, however we do have a
certified partners page where you can find developers for hire. If you make contact directly with an outline of your requirements, they can provide a quote for the work. Thanks.