Solution for POS Terminal (anti-howto in perl)

pos_pricing.pl

use List::Util qw(sum);
use POSIX qw(floor); 

# Pricelist
%P = ( "A" => [1.25, 3, 3], "B" => 4.25, "C" => [1,6,5], D=> 0.75 ); 

# Sale scanning
$_{$_}++ for split (//,qw(ABCDABA));

# Calculate total
print "Total = ".sum map {
	!ref $P{$_} ? $_{$_} * $P{$_} : floor($_{$_} / $P{$_}->[1])*$P{$_}->[2]+($_{$_} % $P{$_}->[1])*$P{$_}->[0];
} keys(%_);