Amount too small = dust = less than 10,000 satoshi - that was simply hard coded for the payments page.
I'd guessed the *00 and *000 amounts per block were too small to get paid out with the next block mined - will they just sit there until the total is > 10,000 sats (mine has been for a while) or until the next block has my %age/shares totally > 10,000 sats ?