Number registers and prices: digits after decimal point

[Karchnu]

Hello,


I want to use groff for invoices. To that end, I need to format numbers
with two digits after the decimal point.
For example, from "100" to "100.00".

I don't think there is a relevant format, currently.
https://www.gnu.org/software/groff/manual/groff.html#Assigning-Formats

Did I miss something? Do you have a solution (or a workaround)?


Also, I would like to create invoices in French, where the dot (".")
actually is a comma (","), but I may be able to hack this, probably.
And for "big" numbers, it should be written this way:
  From "1,000.00" to "1 000,00" (French style, with a space)


Thanks!