Using Silverstripe 2.4.5

I am having trouble getting GST and/or shipping to reliably work. I have tried several times on a pristine site and I cannot get it to reliably work. Some of it could be due to errors in the config settings supplied with ecommerce, e.g.:

SimpleShippingModifier::::set_charges_for_countries(array('US' => 10,'NZ' => 5));
TaxModifier::::set_for_country($country = "NZ", $rate = 0.15, $name = "GST", $inclexcl = "inclusive"))

should be? :

SimpleShippingModifier::set_charges_for_countries(array('US' => 10,'NZ' => 5));
TaxModifier::set_for_country($country = "NZ", $rate = 0.15, $name = "GST", $inclexcl = "inclusive");

But even with these changes I do not get the GST or shipping charges showing up on my shopping cart when I go to the checkout. (I am just using the default products.)

Do I need to clear the shopping cart before seeing these changes (I remove items from the shopping cart and re-add but this doesn’t work)? If so, how?

I am logging in to the shopping cart using the CMS details. Do I need to setup a different account?

Thanks,
Graeme McKinstry