All calculations done by Megamegalomane92. Thank you, Mega!

Good rounding means +1 in a stat

Level up	"Probability" to get a good rounding (%)			
100		99
50		74
75		61
25		60
20		59
40		59
60		59
80		59
10		54
30		54
70		54
90		54
---------------------------
11		45
31		45
71		45
91		45
21		40
41		40
61		40
81		40
76		39
26		38
51		25