Try setting attribute 6 in your dictionary entry to DECIMAL then run HS.UPDATE.FILEINFO at TCL:
>ED DICT MYFILE I.PAY
10 lines long.
----: 6
0006:
----: R DECIMAL
0006: DECIMAL
----: FI
Check out Rocket's ODBC documentation (page 75-76) for how to optionally set custom precision and scale in the dictionary entry for the DECIMAL SQL Data Type.