Good day, Laurie! Thank you for your question. May I suggest that you include a TN before your table explaining that "all numbers are dollar amounts" or "each number in the following table is preceded in print by a dollar sign"? Then perhaps you could omit the currency symbols in the braille and so avoid code switching altogether.
If you feel that you must use Nemeth Code, then I would suggest using a set of Nemeth Code switch indicators for each dollar value.
How does all that sound?