Rounding up a number so that it is divisible by 5

Question

I want to round up a number (decimal) so that it's divisible by 5.

For example, I have a few numbers and the numbers after rounding up:

Number        Rounded
0.4           5
3.4           5
7.3           10

I can use ceil to convert this double to int and use a while loop to get them to the next multiple of 5, but I was wondering if there is any clever way of accomplishing this.

Thanks.

Answer 1

You could first divide by 5 and then use Math.Ceiling to round the value. Afterwards, u can multiply by 5 again.

int rounded = (int) Math.Ceiling(Number / 5) * 5

Answer 2

If you want

 f[6]  =  10
 f[-1] =  0  
 f[-6] = -5

Sören's answer is OK.

If instead you want:

 f[6]  =  10
 f[-1] =  -5 
 f[-6] = -10  

you could do something like:

f[x_] := Sign[x] Ceiling[Abs[x]/5] * 5  

C#:

var rounded = (int) Math.Sign(x) * Math.Ceiling(Math.Abs(x)/5) * 5;