Yes, ACT rounds a .5 up, which is mathematically correct. So a 33.5, 33.75, 34.0, and 34.25 all are reported as a 34 composite.
But it doesn’t really matter - adcoms look at your full score report - the composite isn’t really than meaningful, given it’s lack of granularity. You can be sure a 33/32/32/32 has a leg up on a 32/32/31/31, in terms of ACT performance, despite identical “32”s.
This is one of the reasons that a “perfect” 36 composite is much more prevalent than a 1600 SAT - you can have two 35s or a single 34.
Per the concordance, a 36 is a 1590, though you see 1570-1600 all map to 36. Most ACT scores map to 4 SAT scores, corresponding to the four decimal scores before rounding.
That’s all for individual scores. School reporting may take the average off all the rounded composite scores or all the individual component scores. Assuming an even distribution, the difference should be 0.125, so I don’t think it matters that much. Averaging the composites give the higher score, and is easier, so that’s probably what they do.