I tested it dave and these are my results,
1=0
2=1 minimal 5 maximum
3=2 minimum 10 maximum
4=3 minimum 15 maximum
5=4 minimum 20 maximum ******* as you can see 5 and 6 are the same
6=4 minimum 20 maximum
7=5 minimum 25 maximum
8=6 minimum 30 maximum
9=7 minimum 35 maximum
10=8 minimum 40 maximum