Double check `quantile_to_interval.dataframe()`

There is this line of code: 

```
  dt[, range := ifelse(
    boundary == "lower",
    round((1 - 2 * quantile) * 100, 10),
    round((2 * quantile - 1) * 100, 10)
  )]
```
I'm not entirely sure we want to do rounding there? 
