This article explain how to set minimum price when selling the the product.
Step 1. Select Module on Setup Menu
Step 2. Tab Sell then go to product dialog - price minimum type
A. For not lower than unit Price
B. For not lower than Unit Cost
II. Setup for user
Step 1. Select Group on Users Menu
Step 3. Tab Sell - More Permission - Tick "Price Minimum" then Update
Step 1. Go to "Sell" and " Input Product"
Example: Cashier will sell product with unit price is 300.000 and try put price lower with put price 50.000 and DealPOS will be notification.