Hi,

1. Define Fields with Precision.

Use fields.Float for general decimal numbers, specifying precision with the digits attribute (e.g., digits=(16, 2) for 2 decimal places, or digits='Product Price' for named precision).

Use fields.Monetary for currency amounts, which automatically uses the precision of the associated currency_id field.

2.Perform Calculations Safely:

Odoo's ORM generally handles underlying decimal.Decimal objects for precision.

For explicit rounding in Python code, use odoo.tools.float_round(value, precision_digits=X) to ensure consistent rounding behavior.

3.Display Decimals in Views and Reports:

XML views and QWeb reports automatically apply the precision defined on the field.

Use widget="monetary" in XML for monetary fields to ensure proper currency formatting and decimal display.

In QWeb, t-field with t-options='{"widget": "monetary", "display_currency": record.currency_id}' or t-options='{"widget": "float", "precision": X}' can be used for precise display.

Hope it helps.