Definition of Rounding error:
Error caused by approximating a figure (number) with fewer digits from an original figure with more digits. For example, rounding off 99.987 to 100. Whereas rounding-errors may be harmless in manual computations, they can become serious-mistakes in computer calculations involving thousands or millions of mathematical operations. Also called roundoff error. Compare with truncation error.
A rounding error, or round-off error, is a mathematical miscalculation or quantization error caused by altering a number to an integer or one with fewer decimals. Basically, it is the difference between the result of a mathematical algorithm that uses exact arithmetic and that same algorithm using a slightly less precise, rounded version of the same number or numbers. The significance of a rounding error depends on the circumstances.
While it is inconsequential enough to be ignored in most cases, a rounding error can have a cumulative effect in the present-day computerized financial environment, in which case it may need to be rectified. A rounding error can be especially problematic when rounded input is used in a series of calculations, causing the error to compound, and sometimes to overpower the calculation.
Meaning of Rounding error & Rounding error Definition