Documentation
Round towards the nearest value allowed with the current
precision. If the current value is exactly halfway between two logal
values round away from 0.
Source
(defun round-half-up (number &optional (precision *precision*))
"Round towards the nearest value allowed with the current
precision. If the current value is exactly halfway between two logal
values round away from 0."
(multiple-value-bind (value discarded)
(floor (* number precision))
(if (<= 1/2 discarded)
(/ (1+ value) precision)
(/ value precision))))
Source Context