Nested If function

I had this working before to a certain extent, then I changed something and it all went wrong
=IF(H12<=0,"0%",IF(H12=3<="5","10%",IF(H12=6<=10,"15%","20%")))

What I need is, that if 0 is in cell H12 "0%" is shown, if it is between 1 and 2 then "5%" is shown (I know I have completely missed it out of the formula, I realised after pasting it here, but that is not what the problem is) if it is between 3 and 5 then "10%" is shown, if it is between 6and 10 then 15% is shown and if it is anything else then 20% is shown.

Try:

=LOOKUP(H12,{0,1,3,6,11},{0,.05,.10,.15,.20})

formatted as Percentage.