Take the numbers 0,1,2,3,4,5,6,7,8,9,10.
Is five closer to 0 or 10?
Five is the half way point.
To round up means to assume that 5 is closer to 10 than it is closer to 10, BUT ITS NOT. ITS THE HALF WAY MARKER.
It should be a mathematical law that it's simply not applicable to judge a digit [n + 1/2] closer to [n + 1] than to [n].
If you want to round up or down use a base that has an odd amount of numbers. Like base 9.