Endicia has a minimum purchase of $10 to top off your postage balance. Of course, sometimes you won't need $10 to purchase all of your remaining labels for the day. Not to worry!
The remaining postage will stick around in your postage balance. It will be waiting for you to use next time you're shipping packages.
What is Endicia?
How to: View my postage balance
How to: Add more postage to my Endicia carrier accounts
How to: Refund an Endicia postage balance if I added too much
Why can't I buy labels with an exact amount in my account?