Pleas post a complete program (and data) that demonstrates your problem. I cannot duplicate it.

use strict;
use warnings;
*IN = *DATA;
my $row;
my $val;

while ( $row = <IN> ) {
    $val = substr( $row, 0, 1 );
    my @tranAmount = substr( $row, 68, 17 );

    foreach (@tranAmount) {
        print "$_\n";
    }
}
__DATA__
0                                                                   10
+.00000000000000
0                                                                   10
+.00000000000000
0                                                                   10
+.00000000000000
-                                                                   -3
+0.0000000000000
[download]

OUTPUT:

10.00000000000000
10.00000000000000
10.00000000000000
-30.0000000000000
[download]

UPDATE: Corrected formatting tag