To the OP:
In addition to the commentaries cited by Keeve, Malbim (a 19th century rabbi) suggests that the specifics listed from verses 7 through 10 are only those vessels that were removed from the temples of Nebucadnezzar’s gods, and the total in verse 11 includes all vessels brought by Sheshbazzar, which includes vessels obtained from other sources as well.
septimus:
I’d always learned that the unnamed 70th person was Yocheved, daughter of Levi, which the Midrash says is indicated by Numbers 26:59.
ftg:
Not really, not in that census - it was rounded to 100s, but the tribe of Gad had exactly 50 left over in their hundred, so the exact halfway point sort of defies proper rounding. (The modern rule to round those upward was not in use in Biblical times.)
The later census in Numbers 25 is a bit stranger, as the tribe of Reuben is counted to 30 past the nearest hundred, but all the others are in even hundreds. Either they’re rounding to 10s and all other tribes coincidentally round to 00, or Reuben was treated differently to emphasize that they lost 250 citizens in the Korah rebellion, something mentioned in Reuben’s section of the census.
I suppose there’s also the extremely unlikely possibility that there is no rounding, and all tribes had populations that could be divided by 10, and in most cases, by 100, but I wouldn’t assume so.