This is such a common question, and I myself looked for help with this a while back. I ended up using the code from Natalie Vernon Rounding for currency • Activity Builder by Desmos, and made an inadequate activity that shows the correct “money” answer after submission.
Serge Ballif made a calculator workaround but I don’t really know what I am doing to understand how to check the answers against it. Graphing Calculator Wait, here it that converstation?–Controling for the number of decimal places - #4 by Daniel_Grubbs
I made this from the code by Jay for integer practice, but I am sort of embarrassed to post it. However, my gut says someone here who is really good at the code might talk me through how to fix it, so it checks against the answer correction rather than just posts it. Rounding Currency • Activity Builder by Desmos