You tried those fixes where?
If your table field is single or double data type set to 3 places and your query is a Totals query using Sum, and that field is set to Currency (query property sheet) and the decimal count is set to 3 in the query, I would think it ought to work. Warning - if you switch to single or double in the table from some other type, you might introduce floating point errors so only play with a copy of your table.
If you find that works, you can always update your "fixed" table (assuming you've altered the number type) using your original table via update query but I would even perform the update on a test copy first.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.