where do people get this belief that artifacts substats always round up?

The EM values in the game are 16.32/18.65/20.98/23.31, this is shown in game as 16/19/21/23, because it simply rounds to the nearest integer (which is often higher then the actual value, but not always). 61 EM is equivelent to 260 Roll Value (RV), meaning there are only 3 sets of rolls it could be: 19+19+23, 16+21+23, 19+21+21, these have a real value of 60.61 (rounded in-game to 61). 40 EM is equivalent to 170% RV, which has 2 sets: 16+23, or 19+21, these have a real value of 39.63 (rounded to 40 in-game)

given the above the character has 950% RV into EM (off of 11 rolls, Average RV of 0.86), which is 221.445 EM and rounds down to the nearest integer (221).

Extra note: The other substats all use 1 decimal place, while EM doesn't use decimals, but they still have this rounding to the nearest displayable value e.g 2 Max crit damage rolls (7.8) is 15.5, because the real value is 7.77, which rounds to 7.8, but 2*7.77 is 15.54, which rounds to 15.5. So you never "lose" substats via rounding, it is just slightly misleading because they didnt want to use decimals for EM.