In SQL Server, can we set if it rounds or truncates by default?

I have a large number of inserts and updates coded in my program that involves money, and I cam across a serious rounding bug. The majority of the time, I want to truncate the values, instead of the SQL Server default of rounding.

Rather than changing all my existing code, is there a way I can set this at a column level? Table level? Server level?

Edit: Sorry, the column type is a decimal(10, 2). Example: I want to enter 100.555 and either make it save as 100.55 or 100.56, as it currently rounds.