[Endoperez]

Rerolls are actually made with a dice that's 'numbered' 0-5. IIRC, probability of rolling anything under 6 with one open-ended dice is equal, and probability of getting anything above 5 and below 12 is equal, etc.

So something like:
5/6 chance of result 1-5.
1/6 chance of first 6; 1/6*5/6 chance of a result 6-10
1/36 chance of second 6; 1/6*1/6*5/6 chance of a result 11-15


Then I tried thinking about two dice, and gave up and decided that the manual table is good enough.