I want to update prices in price book (tdpcg0131m000) with alll records with 5% off, but we intend to keep all new prices with 2 decimal places only.
I found a session (tcmcs0553m000) "Rounding Codes", but I don't understand how to work with it.
Could anyone know how to use it?

Can't you just use the function round() before storing the value? Or are you looking to force the domain to 2 places?

If you create a rounding code with rounding value as 0.01 then you should get the required result.

Regards, Adriaan