This type of rounding is based on a logarithmic scale defined by a fixed non-zero real scaling factor "s" (in most frequent cases this factor is "s"=1) and a fixed positive base "b">1 (not necessarily an integer and most often different from the scaling factor), and a fixed integer number "n">0 of significant digits in that base (which will determine the value of the increment to use for rounding, along with the computed effective scale of the rounded number).