The Manage Trips feature in TG allows vehicle logbooks to be created, and trips assigned as either Business or Private. 

The Australian Tax Office (ATO) require a reason/comment on each business trip. For this reason trips will default to Private.

If you have many trips all for the same business reason, you can create a trip type under Admin -> Trip Types

Then you can select all trips in the Manage Trips window and set them to this trip type at once.