QuoteSo just a 2.88K display? Or does that get rounded to 3K? so isn't a 2.5K display also 3K then?
It seems it's less about rounding up and more about defining an acceptable range for one "K" worth of resolution.
If you accept "1K" to be in the ballpark of 1000 pixels of width, e.g. 960-1024, then 2880 (960x3) would be "3K" in the same sense that 3840 (960x4) is accepted as "4K".
2560 can't be "3K" because dividing 2560 by 3 yields 853(.33...) which is far below 1000. It also can't be "2K" as per various promotional sources, because 2560/2=1280 is far above 1000. It can be "2.5K" (1024x2.5), though, in the same manner that we treat 5120 (1024x5) as "5K".
I'd agree that simply dividing by 1000 (2.56K, 2.88K, 3.84K, etc.) would be the least confusing solution of all!