A powerful feature for approvals would be to allow a GP% to be set, which would apply to sales records(quotations, orders, invoices etc). This would be a "Less than" field rather than "Up to". This would be checked against the total GP% on the sales record.

For even more functionality, there could be the option to check the GP% at row level, so that if any item line was below the set GP%, it would require approval. However for this to work, there would also need to be some kind of filter on the item or item group as some items are always going to have a low GP% that do not need approval.