Every line item in the invoice wizard's Details step has editable Unit Price and Total fields. Click directly on either field to edit inline. Changing Unit Price recalculates the Total automatically (quantity × unit price). Changing Total recalculates the Unit Price automatically (total / quantity).
This is useful when you've agreed to a one-off price that doesn't match any of the customer's standing rates. Maybe the site rate is $85/month per unit but you negotiated $500 flat for the cycle. Set the Total to 500 and the system handles the math.
When you override a price away from what the pricing waterfall resolved, the source badge on the line changes to "Custom" so it's visually obvious you've deviated from the system's resolved value. Reverting to the original value (or removing and re-adding the line item) restores the original badge — "Site rate," "Customer rate," or "Catalog rate" depending on which layer was used.
Custom prices on an invoice line item don't update the Rate Card or Customer Default Rates. They're one-off overrides for this invoice only. If the new price should apply going forward, update the Rate Card row or Customer Default Rate so future invoices pick it up automatically.
Draft invoices preserve your edits. You can save a draft, leave, come back later, and the unit price and total will be exactly what you set. The Review step and PDF preview reflect your edited values before send.