How is this a rounding error?

I mentioned earlier that the Democrats’ math does not add up when it came to jobs numbers.

Congressman Eric Cantor has prepared a chart that shows just how screwed up the White House’s numbers are. The White House attributes the error to a rounding error. That doesn’t quite add up though.

Small states have significant deviations from totals by the state versus total by the congressional district. And states with just one state wide congressional district have +20% swings.

Is this the same type of math and rounding they’ll use for census numbers?