Pine language becomes more and more flexible! Now you can define step size for each input:

study(title="Parabolic SAR", shorttitle="SAR", overlay=true)
start = input(0.02, step=0.01)
increment = input(0.02, step=0.01)
maximum = input(0.2, step=0.1)
out = sar(start, increment, maximum)
plot(out, style=cross, color=blue)

You can read more about Pine Script Language in the Pine Script Tutorial and in the Pine Script Reference