OpenAI Ads Events and currency’s lowest denomination

I’m not sure where the new OpenAI Ads pixel and conversions API questions should go?

The documentation for adding amounts to the Ads events states:

“Event-level monetary value in the currency’s lowest denomination.” - Supported events - Event data shapes

The system I work on lets you set the number of decimal places for each currency and, therefore, its lowest denomination on a per-website basis. OpenAI would not know that, so it would not know how to calculate the true amount.

How does OpenAI Ads decide the lowest denomination decimal places per currency? How do we ensure we do the same?