sql server 2008 datetime data types

hi experts,

I'm using sql server 2008 R2.

When I run this query:


DECLARE @datetime datetime = '2013-04-05 16:32:35';

DECLARE @datetime2 datetime2 = @datetime;
DECLARE @smalldatetime smalldatetime = @datetime;

SELECT @datetime2 AS '@datetime2', @datetime AS '@datetime', @smalldatetime AS '@smalldatetime';

I get the following result:


What data type should I use to represent a date time value that looks like this?:

2013-04-05 16:32:35

I thought I was supposed to use smalldatetime data type.
But if you look at the image of my query above, when i use that data type the seconds are rounded up.

Am I missing something?
Why are the seconds rounded up in the smalldatetime datatype?

thanks.