I am using the UPS shipping module to get shipping prices from UPS with my negotiated rates.
When you request the shipping, the values returned include the field GrandTotal. Unfortunately this figure does not include any applicable taxes that are added by UPS. This is quite important if your company is not registered for TAX and cannot claim the tax back and want to pass on this TAX cost to your customer.
It would be great if the module had an option to include applicable taxes in the value shown to customer.
In the rating request packet, if the field <TaxInformationIndicator/> within the <RatingServiceSelectionRequest><Shipping> tags is set (not set in the module), then the response includes additional information, including what taxes apply to the shipment (this happens even for negotiated rates, even though the API docs implies it doesnt)
The response that you get back includes the "GrandTotal" field (ex tax) (Where Magento currently gets the total from) but also includes an additional field "TotalChargesWithTaxes" (If you are shipping to somewhere where TAX is added)
If you are shipping to a country where no TAX is applied then the GrandTotal field contains the total shipping amount.
If you are shipping to a country where TAX is applied, then GrandTotal still contains the exTAX price, but the TotalChargesWithTaxes field is included with the TAX added on.
You would need a bit of logic so if TotalChargesWithTaxes is not set, then get total from GrandTotal, otherwise useTotalChargesWithTaxes.