SQL Server Decimal(9, 0) vs INT
I agree that there are no real benefits in terms of storage space as long as you are comparing DECIMAL(9, 0) vs INT or DECIMAL(18, 0) vs BIGINT. (Within a single byte.)

In terms of processing, like @Andriy says the DECIMAL will naturally divide into a type that doesn't lose the fractional part, if that's important to you. 

On the other hand, working with native INT types is much faster from a numerical standpoint if you are doing a lot of SUM()s or comparisons (such as searching on the values) as they are pipelined more efficiently by the CPU. An int comparison is two assembly opcodes (MOV, CMP) but any decimal comparison will be many, many more.