#! perl -slw
use strict;

while( <DATA> ) {
    chomp;
    printf "Before '%s' becomes ", $_;
    s[ ( \d+ )+ (?: \. ( \d{0,2} ) ( \d* ) )? % ]{
        local $^W;
        my $n = substr( $2 . '00', 0, 2 );
        ($1||'') . $n . ( length($3) ? ".$3" : '' );
    }xe;
    print "'$_'";
}

__DATA__
0.781063003540039%
2.25%
1.455%
4.9%
0.79%
75%
1.15%
0.45999999999999996%
0.9199999999999999%
0.22999999999999998%
1.3%