To force close the POS session properly, you can follow these steps:

1.     Check Tax Configuration: Make sure that the tax configurations for your products and orders are correctly set up. Taxes can significantly affect the total amounts. Verify that the tax rates, tax computation methods, and tax accounts are accurate.

2.     Check Rounding Rules: Odoo allows you to configure rounding rules for amounts. Incorrect rounding rules can cause differences between order totals and payment amounts. Make sure that your rounding rules are consistent and accurate.

3.     Verify Payment Methods: Check the payment methods you are using in your POS session. Ensure that the rounding rules, currencies, and exchange rates associated with these payment methods are correct.

4.     Review Decimal Precision: Decimal precision settings can affect how amounts are rounded and displayed in Odoo. Ensure that your decimal precision settings match your requirements.

5.     Adjust Payment Amounts: In some cases, it might be necessary to adjust the payment amounts manually to match the order totals. This should be done cautiously, as it's generally better to identify and resolve the underlying configuration issues.