For receipt and delivery notes, the amount and tax rates are determined either manually, or based on price list data, or from goods cards.
In addition to the above methods for setting amounts and tax rates, the Set amounts... group function (also called Set prices) is available for the goods of an open delivery notes.

This function can also be called through the context menu.

The Set prices... window for the receipt note:

For the delivery note:

If you set the coefficient in one of the fields, then when the cursor is placed in another field, the system will automatically calculate other coefficients relative to the specified one.
In our example, the value is set to -10%, the calculated coefficient is 0.9 and the discount/markup is -622,8.

The amounts in delivery notes are set relative to the value received in the Coefficient field. Each document's line is multiplied by the value from this field.

You can also change the tax rates of the selected goods using the Set amounts… function. For this:

To change the tax rate for all goods in the document, you do not need to select them.