Your password generator is unlikely to be doing this, use ' instead of " for your test, or get the test data from a __DATA__ section instead. If its a generated string, there won't be interpolation, f.e.

#!/usr/bin/perl -w
use strict;

my $user="bobjones";
my $password='abc$123a';

test($user,$password);

sub test {
    my $user = shift;
    my $password = shift;

    print "$user - $password\n";
}
[download]

or

#!/usr/bin/perl -w
use strict;
use String::Random;

my $user="bobjones";
my $password= generateme();

test($user,$password);

sub test {
    my $user = shift;
    my $password = shift;

    print "$user - $password\n";
}
sub generateme {
    my $random = String::Random->new();
    return $random->randpattern('ss!ccnC!cncc');
}
[download]

Using String::Random in place of your random password generator. It will produce strings containing @s, %s and $s, without the need of interpolation.