The following code may not be any shorter than yours, but I find it much easier to understand. The tests demonstrate that it produces the same total as yours for a variety of weights. 
use strict;
use warnings;
use Test::More tests => 11;


my $min   =  1;
my $price = 10;

sub total {
    my $wt = $_[0];
    my $Total
        = ($wt < -$min) ?  $price * $wt 
        : ($wt < 0    ) ?  $price * (-$min) 
        : ($wt < $min ) ?  $price * $min
        :                  $price * $wt
        ;
    return $Total;
}

sub refrence {
    my $wt = $_[0];
    my $nwt = abs($wt);
    $nwt = $min if $nwt<$min;
    my $total = $nwt*$price;
    $total = -$total if $wt<0;
    return $total;
}

for (0..10) {
    my $trial_wt = .3 * ($_ -5);
    is( total($trial_wt), refrence($trial_wt), "Weight: $trial_wt");
}

[download]

OUTPUT:

1..11
ok 1 - Weight: -1.5
ok 2 - Weight: -1.2
ok 3 - Weight: -0.9
ok 4 - Weight: -0.6
ok 5 - Weight: -0.3
ok 6 - Weight: 0
ok 7 - Weight: 0.3
ok 8 - Weight: 0.6
ok 9 - Weight: 0.9
ok 10 - Weight: 1.2
ok 11 - Weight: 1.5

[download]
Bill

In reply to Re: Some simple math and absolute values by BillKSmith
in thread Some simple math and absolute values by sidmuchrock

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.