Can the Time base (minutes) be changed to 5 min intervals?

Hi, would it be possible to adjust the Appointment + Plugin to allow for a minimum interval of 5 minutes?

As i have an appointment on Tuesday that needs to start at 20:10 and one on Saturday morning that needs to start at 09:45 and the current system of 10/15... wont allow me to set both. only one or the other?