Thanks for reaching out to the Google Ads API Forum.
Kindly note that the value of the conversion for the advertiser to be passed as conversion value is double as seen in below screenshot. Adding float value could result in an error in your API request. So what we recommend is you use double value to upload conversion value for your conversions. You mentioned that sometimes monetary values getting munged when stored in a floating point value, then you may implement to check if value is indeed double and if not, you may implement post processing on your end to parse into double.