How to produce numbers in some step bounds?

I want to produce numbers with some steps, for example for step 4, i want to produce:

1   -> 0
3   -> 4
4.1 -> 4
15  -> 16
etc.

for step 0.2:

1     -> 1
3     -> 3
4.1   -> 4.2
15.99 -> 16
etc.

Do you know nice formula to produce numbers like these?开发者_JAVA技巧

It looks like you just want to round() to the nearest multiple of step. Try this:

result = round(num/step)*step

Step 4:

• round(1/4)*4=0*4=0
• round(3/4)*4=1*4=4
• round(4.1/4)*4=1*4=4
• round(15/4)*4=4*4=16

Step 0.2:

• round(1/0.2)*0.2=5*0.2=1
• round(3/0.2)*0.2=15*0.2=3
• round(4.1/0.2)*0.2=21*0.2=4.2
• round(15.99/0.2)*4=80*0.2=16