POS Terminal (Perl solution)

pos.pl

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

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

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

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