Since SORT does not do rounding
, why do you think you are getting it "rounded as 4"?
If you need rounding, you have to code it yourself. Something like this (untested):
The 3Z will put three zoned-decimal zeros in the first three positions of your field. The first IFTHEN will add one to the first six digits of your source number and store the result after the three zeros. The second, like an ELSE, will just store the first six digits after the three zeros.