Editing Rounding (section)

===Rounding to a specified multiple===
The most common type of rounding is to round to an integer; or, more generally, to an integer multiple of some increment – such as rounding to whole tenths of seconds, hundredths of a dollar, to whole multiples of 1/2 or 1/8 inch, to whole dozens or thousands, etc.

In general, rounding a number {{mvar|x}} to a multiple of some specified positive value {{mvar|m}} entails the following steps:
:<math>\mathrm{roundToMultiple}(x, m) = \mathrm{round}(x/m) \times m</math>

For example, rounding {{math|1=''x'' = 2.1784}} dollars to whole cents (i.e., to a multiple of 0.01) entails computing {{math|1=2.1784 / 0.01 = 217.84}}, then rounding that to 218, and finally computing {{math|1=218 × 0.01 = 2.18}}.

When rounding to a predetermined number of [[significant figures|significant digits]], the increment {{mvar|m}} depends on the magnitude of the number to be rounded (or of the rounded result).

The increment {{mvar|m}} is normally a finite fraction in whatever [[numeral system]] is used to represent the numbers. For display to humans, that usually means the [[decimal|decimal numeral system]] (that is, {{mvar|m}} is an integer times a [[power (mathematics)|power]] of 10, like 1/1000 or 25/100). For intermediate values stored in digital computers, it often means the [[binary number|binary numeral system]] ({{mvar|m}} is an integer times a power of 2).

The abstract single-argument "round()" function that returns an integer from an arbitrary real value has at least a dozen distinct concrete definitions presented in the [[#Rounding to integer|rounding to integer]] section. The abstract two-argument "roundToMultiple()" function is formally defined here, but in many cases it is used with the implicit value {{math|1=''m'' = 1}} for the increment and then reduces to the equivalent abstract single-argument function, with also the same dozen distinct concrete definitions.