2 3 . 5 ▁gets ▁rounded ▁to ▁− 2 4 . ▁ ▁This ▁can ▁be ▁more ▁efficient ▁on ▁binary ▁computers ▁because ▁only ▁the ▁first ▁omitted ▁bit ▁needs ▁to ▁be ▁considered ▁to ▁determine ▁if ▁it ▁r ounds ▁up ▁( on ▁a ▁ 1 ) ▁or ▁down ▁( on ▁a ▁ 0 ). ▁This ▁is ▁one ▁method ▁used ▁when ▁round ing ▁to ▁significant ▁figures ▁due ▁to ▁its ▁simplicity . ▁ ▁This ▁method , ▁also ▁known ▁as ▁commercial ▁round ing , ▁tre ats ▁positive ▁and ▁negative ▁values ▁symmet r ically , ▁and ▁therefore ▁is ▁free ▁of ▁overall ▁positive / negative ▁bias ▁if ▁the ▁original ▁numbers ▁are ▁positive ▁or ▁negative ▁with ▁equal ▁probability . ▁It ▁does , ▁however , ▁still ▁have ▁bias ▁away ▁from ▁zero . ▁ ▁It ▁is ▁often ▁used ▁for ▁currency ▁convers ions ▁and ▁price ▁round ings ▁( when ▁the ▁amount ▁is ▁first ▁converted ▁into ▁the ▁smallest ▁significant ▁sub div ision ▁of ▁the ▁currency , ▁such ▁as ▁c ents ▁of ▁a ▁euro ) ▁as ▁it ▁is ▁easy ▁to ▁explain ▁by ▁just ▁considering ▁the ▁first ▁fraction al ▁digit , ▁independently ▁of ▁supp lement ary ▁precision ▁digits ▁or ▁sign ▁of ▁the ▁amount ▁( for ▁strict ▁equivalence ▁between ▁the ▁pay ing ▁and ▁recip ient ▁of ▁the ▁amount ). ▁ ▁Round ▁half ▁to ▁even ▁A ▁tie - bre aking ▁rule ▁without ▁positive / negative ▁bias ▁and ▁without ▁bias ▁toward / away ▁from ▁zero ▁is ▁round ▁half ▁to ▁even . ▁By ▁this ▁convention , ▁if ▁the ▁fraction al ▁part ▁of ▁ ▁is ▁ 0 . 5 , ▁then ▁ ▁is