How to round up to the nearest 10 (or 100 or X)?

Question

I am writing a function to plot data. I would like to specify a nice round number for the y-axis max that is greater than the max of the dataset.

Specif

Answer 1

The round function in R assigns special meaning to the digits parameter if it is negative.

round(x, digits = 0)

Rounding to a negative number of digits means rounding to a power of ten, so for example round(x, digits = -2) rounds to the nearest hundred.

This means a function like the following gets pretty close to what you are asking for.

foo <- function(x)
{
    round(x+5,-1)
}

The output looks like the following

foo(4)
[1] 10
foo(6.1)
[1] 10
foo(30.1)
[1] 40
foo(100.1)
[1] 110