rounding error

rounding error

1. The difference between an exact mathematical value and the value that is approximated during a calculation or computation in which rounding occurs. So many of the values we have to use in these calculations have decimals that extend to an infinite length that rounding errors are simply unavoidable. It may seem like we leave a very large rounding error when we use 3.14159 as the value for pi, but in most instances it will give us a result that it accurate enough for our purposes.
2. A figure that is or seems large in isolation but is relatively small or immaterial to a large company. The settlement of $300,000 is little more than a rounding error to a global corporation that earns billions of dollars each year. I'm nervous about asking for a raise, but I'm trying to tell myself that it is just a rounding error in the company's eyes.
See also: error, round
Farlex Dictionary of Idioms.

rounding error

a large amount of money that is relatively small in comparison to a much larger sum. To a large company like Smith & Co., a few thousand dollars is just a rounding error. It's not a lot at all.
See also: error, round
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • big things come in small packages
  • package
  • the best things come in small packages
  • good things come in small packages
  • best things come in small packages, good things come in small packages
  • put (something) at
  • put at
  • the best things in life are free
  • best things in life are free
  • all the tea in China
References in periodicals archive
PRELIMINARY EVIDENCE ABOUT ROUNDING ERROR AND STOCK SPLIT FREQUENCIES
Although rounding errors prevent LAPACK subroutine DGEEVX from preserving the Hamiltonian eigenvalue plus-minus pairs, the tables below report only the computed eigenvalues with nonnegative real part.
Thus, a blue or green pole has a good chance of being genuine and useful for approximation, whereas pink and red poles are likely to be artifacts introduced by rounding errors.
The number and percent distribution of workers paid hourly rates at or above $7.15 for regions and divisions were derived from State totals and may therefore include slight rounding error. It is not possible to determine definitively whether workers surveyed in the CPS are actually covered by the Fair Labor Standards Act or by individual State minimum wage laws.
Salamon said the tools will help nations improve their overall understanding of the size and scope of their nonprofit sectors, which had been regarded as little more than rounding error statistically in the past.
Asked about the 70 percent tax plan in an interview earlier this month, Bill Gates, formerly the richest person in the world, made another interesting point saying that "you wouldn't want to just focus on the ordinary income rate, because people who are wealthy have a rounding error of ordinary income", suggesting that the estate tax and taxes on capital would be more effective in collecting more taxes from the ultra-wealthy. 
By having the new point, and the Self-Rated Poverty (SRP) percentages of 51 last March, 51 last June, and 50 last September, we know that poverty has been flat in the last four quarters, and that it averaged 50 percent in 2015 (corrected for rounding error).
For most companies, $1 million isn't even a rounding error.
This was not even a "rounding error" for manufacturers, Darby said.
(While these sums are rounding error to most CFOs, they are life itself for non-profits.) What explains this $3.23-to-$1.00 leftward tilt?
"That's a rounding error" for the nine media giants that funded NCN, Ingle said.
And all of these digital currencies add up to a rounding error in my mostly stock-based investment portfolio.
One week's worth of lost sales is a drop in a bucket that will probably be written off as a rounding error in this year's financial reports.
We will compare existing bounds and we will demonstrate necessity of a proper rounding error analysis: we present an example of the well-known bound which can fail in finite precision arithmetic.