Jeff Moden (8/1/2008)
It depends... if you're not going to do anything to the values other than add or subtract... no problems. If you're going to do anything else (like multiply or divide), you'll need at least 4 decimal places to do the calculations without loosing overall accuracy.
The MONEY type has 4 decimal places - but the real answer depends on the degree of accuracy you need. Be careful about implicit conversions involving money if you need greater precision than 4 decimal places: http://tinyurl.com/59s2dn
There are also subtle performance differences between the two types - Aaron Betrand blogged about these (targeted at SQL Server 2008 but should hold fairly true for previous versions): http://sqlblog.com/blogs/aaron_bertrand/archive/2008/04/27/performance-storage-comparisons-money-vs-decimal.aspx
Regards,
Jacob