float is an approamite datatype. It consists of a 53-bit mantissa and a
nine-bit exponent. That permits us to store a very broad range of
numbers. From 1E310 to 1E-310. The price is that far from all decimal
numbers can be represented exactly.

When a floating-point number is presented, it appears that different
applications are more or less zealous to show the decimals. If you were
to look at that column from Query Analyzer, the query tools that came with
SQL 2000, you would probably see that random noise at the end. QA shows
more decimals than Mgmt Studio does.

What is the best suggestion for your case I don't know, but you should
probably ask in a newsgroup where DataGridView is popular.