PayPal - How to fix error Transaction refused because of an invalid argument.

Error

     10401
    Transaction refused because of an invalid argument. See additional error messages for details.
    Order total is invalid.

Looks like PayPal doesn't like money data type.
When converting money to string - it will produce number with  4 decimal points.  Pay pal likes 2 decimal points.
So when sending them transactions info, ensure both total and line items have only 2 decimal points


watch complete example on YouTube