0.09

Then set the value of the cell to this equation:

=floor(33.8, 0.1)

The equation truncates the hundredths place, the formatting sets the hundredths place to a 9. So the final solution will look like this:

Put your list of numbers somewhere else, like on an unused worksheet. Enter the formula '=floor(<first cell in your list>, 0.1)' into the first spot where you want your list of numbers to be. Copy the formula down X cells so it picks up the entire list floored where you want it to be displayed. Then highlight those cells, right click, format cells, and set them to custom formatting with a format string of 0.09.

They will now display with their hundredths place set to a 9 always. The value in the cell will be the original value floored to the tenths digit. The original value will be wherever your hidden list is.