if you would like to set a rounding method for cash, you can follow the next steps:
Go to Point of Sale ‣ Configuration ‣ Settings and enable Cash Rounding, then click on Save.
Go to Point of Sale ‣ Configuration ‣ Point of Sale, open the point of sale you want to configure, and enable the Cash Rounding option.
More info is available on:
Or use the solution within Monetary fields as proposed by Haresh Kansara:
I think if you are dealing with Monetary fields, then you dont need any code change, only need to set proper
Steps to change Subtotal fields (Monetary) decimal accuracy from 2 digit to 3 digits:
1. Activate Multi Currency from General Settings (Settings > General Settings > Accounting ('Invoicing' If Community)), Now activate Multi-Currencies from Currencies section.
2. Now go to Accounting ('Invoicing' If Community) > Configuration > Accounting > Currencies.
3. In currency form change value 0.010000 to 0.001000 in Rounding Factor field and save record.
I hope this will helpful.
Odoo Application Engineer”