In general, computers use binary arithmetic and have limited precision. In the same way that we cannot write the result of 1/3 in an exact decimal, some numbers cannot be represented exactly in binary. This causes problems when trying to compare two floating point numbers for exact equality. This is a topic that gets intense study by programmers doing numerical analysis. You can get different results on different computers if the computers have different hardware precision, or other differences in handling floating point numbers (I am not an expert at hardware implementation so I can't give much of an explanation there). In software, if two floating numbers are being compared they are generally compared to match within some tolerance, rather than compared for absolute equality.

Formula: copy to clipboard 
when I double click on the value it doesn't display 0.1


When you double click, it should display the formula. How can it display 0.0999999999999943? How did that number get in the cell, if not by a formula?

Without knowing more about your data I can't suggest why the rounding approach isn't working for you.