order quantity discount calculation

[ecomm]

hi guys and gals
Running zc 1.3.6
Installed order quantity mod which seems to work fine untill you manually add the totals up and relize it dont add up correctly
eg
Sub total $81.45 correct
shippin: $12.10 correct
discount -$8.14 correct
tax @10% $7.69 correct
total $84.60 incorrect when you add this up it should be $85.41

my settings are
uantity Discount
This module is installed - version 1.3
true
Sort Order
295
Include Tax
true
Re-calculate Tax
Standard
Discount Units
percentage
Discount Basis
Total Items in Cart
Discount Level 1
5
Discount Amount 1
10

Now if I change recalulate tax to "none" this changes my total to correct amount but obviously leaves my tax at original calculated amount
Sub total $81.45 correct
shippin: $12.10 correct
discount -$8.14 correct
tax @10% $8.50 correct
total $85.41
any ideas
thanks

[swguy]

I can't dup this. Using your settings, I get the right numbers.

Do you display prices with taxes included? Any other non-US style
settings I may not have tested?

Scott

[ecomm]

I do display prices including tax
Have only one tax setup in one zone which is 10%


Arhhh just spotted wats happening!! not that i know how to fix it but you guys might.
It seems that when i choose to recalulate tax (which is 10%) its adding 10% to the discount price even though it doesnt show it then taking that figure off thoe total price.
EG
$362.00
Sub-Total:


$12.10
Flat Rate (Best Way):


-$36.19 if you were to add 10% here $39.80 so 362+12.10-39.80= 334.30

Quantity Discount:


$30.39
GST 10%:


$334.29 this should be 337.91

Total:

Hope this is explained ok
Also i have another zen cart setup and i just installed this mod there and it does the same thing??
Thanx in advanced
Michael

[swguy]

OK. Try replacing process() in ot_quantity_discount.php with this:

    function process() {
       global $db, $order, $currencies;
       $od_amount = $this->calculate_deductions();
       if ($od_amount['total'] > 0) {
         $show_amt = $od_amount['total'];
         reset($order->info['tax_groups']);
         while (list($key, $value) = each($order->info['tax_groups'])) {
           $tax_rate = zen_get_tax_rate_from_desc($key);
           if ($od_amount[$key]) {
             $order->info['tax_groups'][$key] -= $od_amount[$key];
             if (DISPLAY_PRICE_WITH_TAX == 'true') {
                $show_amt += $od_amount[$key];
                $tax_deduct = $od_amount[$key] - ($od_amount[$key] * $tax_rate/100);
                $order->info['total'] -=  $tax_deduct;
             } else {
                $order->info['total'] -=  $od_amount[$key];
             }
           }
         }
         $order->info['total'] = $order->info['total'] - $show_amt;
         $this->title = '<a href="javascript:alert(\'' . $this->explanation . '\');">' . $this->title . '</a>';
         $this->output[] = array('title' => $this->title . ':',
         'text' => '-' . $currencies->format($show_amt, true, $order->info['currency'], $order->info['currency_value']),
         'value' => $od_amount['total']);
       }
    }

[ecomm]

thanks for the reply
seems you are sorta getting closer to the answer
ok still the discount is a little off
eg
sub total 100
disc. -10
tax 10% 8.18
total 89.18

as you can see the total is still out not by much but the more you add the more it is out

the tax seems to be calculating on the correct total amount of the total eg we work out the gst by total
$90/11 =8.18
90-8.18=81.82 exclusive
81.82+10%=90inclusive
thanks again for your time

ps a quick explaination in the code so i know what why this is happening would be great unless it is more than just a couple of lines