If you want to auto round off final bill value, you can follow these steps:
Step 1: Go to Administration and click on configuration.
Step 2: Choose the Voucher Series Configuration option and select the voucher type that you want to apply the discount for, such as sale, purchase, etc. Then, select the voucher series and click on Voucher Configuration.
Step 3: You will see the Auto Round off Final Amount. feature. Set it to Y to enable it and click on configure button.
Step 4: Here, you can choose Rounding off Mode i.e, Always Upper, Always Lower & Automatic as per the need.
Now, while you save your invoice the bill value automatic rounded off as configured.