Incorrect Maths?

[Wingz]

I've been running ZC for years now and last weekend decided to make things simpler for users, by adding some attributes (trying to accomplish 'one page' selection.

I'm using a combination of radio buttons for mounting, and checkboxes for size as follows.

The cart shows;

Mounting:
Double (represents 2 medals wide) ( +$2.20 )
Quadruple (represents 4 medals wide) ( +$4.40 )
Quintuple (5) ( +$5.50 )
Single (represents 1 medal)
Triple (represents 3 medals wide) ( +$3.30 )

Size:
Full Size
Miniature ( -$2.20 )

But the invoice shows;

2 x Medal Mounting Bars
- Mounting: Double (represents 2 medals wide) (+$4.00)
- Size: Full Size
- Size: Miniature (-$4.00) 10.00% $5.00 $5.50 $10.00 $11.00

So it's adding the $2.20 for the full size - and subtracting the same $2.20 for the mini?

The full size is base price of a single ($5.50) plus $2.20 for the increased size for a total of $7.70, an invoice cost should be $$7.70.
The base price of a mini is $5.50, plus 2.20 for the size increase from single to double, minus $2.20 for the size adjustment for a total of $5.50. The invoice cost should be $5.50.

Invoice total for both is $11.00. It should be $13.20.

Where did I screw up?

[kobra]

Good explanation of what is represented on the front end...
Really need your product settings and where & how you applied to the attributes
A link to this might be of assistance

[Wingz]

Kobra .. thanks ...

Link: http://www.heritagemedals.com.au/ind...roducts_id=166

Attributes snaphot attached.

Thanks.

[kobra]

To be able to order both the full and the mini will require 2 orders

The check boxes allows both to be included but scraps the correct math

Make the check boxes radio buttons and one of them default then a customer can order one or more each size but in a seperate operation

[Wingz]

Thanks Kobra, done that.

On 'continue shopping' after adding the order, is there any way the customer can be redircted back to that product to select more, rather than be directed back to the main site index page?