Javascript: Round up to the next multiple of 5

Like this?

function roundup5(x) { return (x%5)?x-x%5+5:x }

const roundToNearest5 = x => Math.round(x/5)*5

This will round the number to the nearest 5. To always round up to the nearest 5, use Math.ceil. Likewise, to always round down, use Math.floor instead of Math.round. You can then call this function like you would any other. For example,

roundToNearest5(21)

will return:

20

This will do the work:

function round5(x)
{
    return Math.ceil(x/5)*5;
}

It's just a variation of the common rounding number to nearest multiple of x function Math.round(number/x)*x, but using .ceil instead of .round makes it always round up instead of down/up according to mathematical rules.