[Bug]: Rounding on token usage causes us to display 0 in situations where there is 3+ decimals in the float

[alex-mcgovern]

Feedback from @danbarr

Should we remove the cost indicator from the token usage tooltip until we actually have the cost features in place? Seeing "USD 0.00" the natural next question is "how do I set costs?"
this was with OpenAI directly. Was thinking we maybe just needed more precision than two decimals, but at 0.00003/token, 1.6k tokens should round to $0.05?
Might be useful to also extend the precision out one more decimal, for smaller requests?

[davolokh]

i think we have enough space even for 4 decimal points?