Not sure how you define 'very small' but here's one way to do it:
n > 100 ; Round( n ; 0 ) ;
n > 1 ; Round( n ; 1 ) ;
Round( n ; 2 )
But this has to be implemented at the data level, it can't be done at the layout level via Inspector's formatting options.
I was actually wondering if there was some trick within 'formatting', but yes, your method will work through an autoenter field when I import the data. Thanks.