Fritzew

http://docwiki.embarcadero.com/Libraries/Tokyo/en/Data.DB.TBCDField

From the Docs:
 

Quote

TBCDField uses the currency (Delphi) or System::Currency (C++) type to manipulate BCD values. 
This is faster than storing and manipulating the value using a true BCD type, 
but limits the precision of the BCD values it can support to 4 decimal places and 20 significant digits. 

TBCDField converts the data from a BCD value to a currency value when it fetches the data from the database table, 
and converts it from a currency value to a binary-coded decimal value when it posts the data. 
If the underlying database table contains a value that requires greater precision, 
TBCDField raises an exception.

So I think Currency will the correct type to choose