Billing units are based on a 6-minute interval time unit to ensure that your rate is applied appropriately on an hourly basis. 

For example, if you work for 12 minutes, the billing unit would display .2 on the timer. This would mean that 20% of your hour was spent working and would apply 20% of your hourly rate to the charge. 

Here's a break down of billing units:

• 1 Minute = .0167
• 2 Minutes = .033
• 3 Minutes = .05
• 4 Minutes = .0667
• 5 Minutes = .0833
• 6 Minutes = .1