Federal Accounting Standards Advisory Board (FASAB)
FASAB as a slighltly murky relationship with GAAP, but it's "the body that establishes GAAP for federal reporting entities." I believe it publishes what is referred to as GAAP in the document, "Statement of Federal Financial Accounting Standards (SFFAS) 34, The Hierarchy of Generally Accepted Accounting Principles for Federal Entities, Including the Application of Standards Issued by the Financial Accounting Standards Board."
Their FASAB Handbook mentions rounding to three decimal places when required.
The agency should determine whether the proper dollar scale (e.g., whole dollars, hundreds, thousands, etc.) for the cash flow spreadsheets was used. Some program subsidy rates, particularly those for programs disbursing over several years, may be influenced slightly with the scale of the program. Therefore, management should determine whether rounding to three decimal places has no significant effect on the cash flow spreadsheet values and the subsidy rate.
EU Economic and Financial Affairs
The only document that I've found that cites an EU standard is this document entitled Converting to the euro. It says,
National law can bring more detail to rules on rounding as long as this leads to a higher degree of accuracy. For example, some groups of services that are sold in units, such as the telephone, electricity or fuel, may require greater precision. In this case, their unit price could be expressed in three or four decimal places and rounding to the nearest cent may only take place on the total amount.
So I would guess that in the case of utilities to be safe in the EU, pricing to a scale of four decimal places is appropriate and you can only be sure if you round at the end of the transaction.
Use what works for your use case. There is no general rule here. Both are fine:
- store as
- store as
bigint with cents or dollars.