How to round by increment larger than 1? Acctualy, I need the next "ceiling" in steps of 5. Example:
ceiling(c(2.5, 6, 9.9, 10, 11, 14, 15), inc = 5)   #not working
> 5  10  10  15  15  15  20
I tried ceiling(), round() and signif() but I could not figure it out. It's probably a repetition but my research always leads me to increments smaler than 1. 
Thanks in advance!