`Float.round: float -> float`

rounds a float to the nearest integer. I’m looking for a rounding function that lets me round to a given number of decimals. My first idea would be something like:

```
let round2 n = Float.(n *. 100.0 |> round |> fun x -> x /. 100.0);;
# round2 Float.pi;;
- : float = 3.14
```

Any better idea?