Tax (VAT) problems

[Guest]

Hi,

 

I am having some problems with my store (store.mk-broadband.co.uk) it is running osCommerce Online Merchant V2.2 RC1 and I have just upgraded to Paypal IPN 2.3.3 as I wasn't getting any info when a customer placed an order through Paypal.

 

The problem that I have is that all of my products are taxable and as I am in the UK I have set up one tax rate of 17.5%.

 

I have applied this to all of my goods but a couple of the higher value items only display the correct price until you add them to your cart, then they just go crazy. Also when I go through the checkout process VAT seems to be added again.

 

All help greatfully received as this store is meant to be live, and I need to fix ASAP .

 

Thanks

 

Paul