Decimal precision, maximum four digits ?

Hi Guys,

SugarCRM is Enterprise 7.5

I'm having trouble with a decimal field. I want to create this field to enter a currency exchange rate. Which is used for calculation at a later stage. Per definition, this exchange rate has 5 digits after the decimal.
Whenever I manually enter 0.54321 and hit save, I get 0.54320
I tested it with several rates. It always rounds everything after the fourth digit.
Weird that I don't find much about this issue. Is it maybe a global or database setting?
Thanks
Julian