We own an eCommerce application and want to funnel submitted orders from that system into Zoho. We're already calculating tax in our application and just need a way to set it in Zoho.

We tried to use Zoho's tax objects for tax by setting the rates to the same rate as we have on the order however we've discovered that the total tax produced by Avalara (which we use for tax calc) ends up being different from the total tax produced by Zoho Books even though Zoho is provided the same exact rates we get out of Avalara. The difference is pennies so likely due to rounding issues.

Here's a super simple example:

Item1 Subtotal: 14.50

Item2 Subtotal: 12.68

Subtotal: 27.18

Tax Rate: 0.5%

I think what is happening is Avalara is calculating the tax on a per-line item basis:

$14.50 at 0.5% = 0.725 = ~0.07
$12.68 at 0.5% = 0.0634 = ~0.06

Total Tax = ~0.07 + ~0.06 = ~0.13

Whereas Zoho is maybe calculating based on total:

$27.18 at 0.5% = 0.1359 = ~0.14

Is there any way to simply set the tax amount instead of having to define a tax rate that then gets calculated? I would like taxes to be displayed how they are but given more control about the amounts that are there.

I suppose an alternative solution though I think one I'd like to avoid is possible - is to set tax as a separate line item and have the order be tax inclusive instead of exclusive