Thank you very much for that explanation!!!! ... I have terrible eyes so before the UI font thing on another thread the cost was blurry for me!!! sorry for any misinterpretation
5 END for 1 Point is how the rules define the cost and how it's implemented in HD. But you don't have to buy END in increments of 5, so if you purchase +1 END, the cost is 1/5 of a Point....which does not round to 0 -- nothing is free. So +1 END costs 1/5 of a Point, which rounds to 1 Point. Similar for +2 END (2/5 of a Point, rounding to 1 Point)....and +3-5 END.
Apart from general rounding rules in HERO System, abilities like END and STUN have specific considerations regarding nothing for free, so +1-5 END = 1 Point, +6-10 END = 2 Points, and so on. All in accordance with the rules of the system (and something of a PITA to code in).