=IF(MOD(A1,1)<0.25,INT(A1),IF(MOD(A1,1)<=0.5,CEILING(A1,0.5),ROUNDUP(A1,0)))
=IF(A1-INT(A1)<0.25,INT(A1),IF(A1-INT(A1)<=0.5,INT(A1)+0.5,INT(A1)+1))