Rounding e.g. enchantments last x % longer

Does GW round up or down (or takes the exact value) when say an enchantment is increased by x % but the result is a decimal.

e.g. an 18 second enchantment using +20% enchantments mod: 1.2 X 18s = 21.6s, will it round to 20s or 21s? Or will the enchantment last exactly 21.6s?

I've searched the forums and the few threads I found had mixed results, so how does GW round?

I believe it will not round it. It'll be 21.6.