Is there something special that you need to do in order to set the

totaltax

in a sales order/estimate? We have Avalara, but I am opting to use their APIs, instead of their bundle. When I set the

totaltax

it get's set back to 0 after saving it

I've had luck setting both

taxtotal

and

taxamountoverride

at the same time, I think that should both get the

total

to automatically update and for the tax value to stick when you save the transaction

Actually i just set

taxamountoverride

by itself and that seemed to work