Visually track discrete performance intervals

I'm trying to find a way to visually track discrete % complete intervals within an activity. We have milestones related to the % complete of an activity. For example - we have an activity "Paving" the runs for 3 months. We receive payments based on the % complete of that activity - but only at discrete intervals. For that activity, we will receive payments when the activity starts, when it reaches 50% complete, when it reaches 75% complete, and when it is finished. Other activities, such as Excavation, we will receive payments when that activity starts, when it reaches 25%