0.5 + 1.5 + 2.5 + 3.5 + 4.5 + 5.5 + 6.5 + 7.5 + 8.5 + 9.5 = 50.0

偶数丸め
0.0 + 2.0 + 2.0 + 4.0 + 4.0 + 6.0 + 6.0 + 8.0 + 8.0 + 10.0 = 50.0

四捨五入
1.0 + 2.0 + 3.0 + 4.0 + 5.0 + 6.0 + 7.0 + 8.0 + 9.0 + 10.0 = 55.0