question

No, currently only support percentage based taxes. More tax support is planned, but not in the immediate future.

I have another question. Should I use only registered in Merchant settings tax rates or can create dynamically for each line item in the order?

Also, I've try to add taxes by executing next code:

List<TaxRate> taxRates = mInventoryConnector.getTaxRates();
LineItem lineItem = new LineItem();
lineItem.setTaxRates(taxRates);
lineItem.setName("Test Item");
lineItem.setPrice(100L);
lineItem.setUnitQty(1)
mOrderConnector.addCustomLineItem(orderToPay.getId(), lineItem, true);

Unfortunately, this code raises com.clover.sdk.v1.ClientException: status code: 400 cannot update one or more of these fields: LineItem{json='{"taxRates":{"elements":[]},"unitQty":1,"price":100,"name":"Test Item"}', bundle=null, changeLog=null} (In example tax rate list is empty, but even if it with one or more tax rates - the raised exception the same). But if remove adding tax rates for item, code works fine.

Looking forward to hearing from you.