Possible to round up and round down in the same formula?

I currently have a formula that nicely tidies up some prices for me. It rounds to the nearest .05 or .09, so for example 3.43 becomes 3.45 and 8.96 becomes 8.99. The only issue is that I want it to round down, only in the case that the figure just above a round number. So if it's 8.01, I'd like it to round down to 7.99 instead of round up to 8.05. I've attached a spreadsheet that shows my formula, and highlighted the cases that I want it to round down instead.

Can this be done?

Would really appreciate any help. Thanks.