If then statement for only the last digit of changing dollar amounts

I want to make an if then statement that will only have an effect on the last digit of a dollar amount (the cents) so in $7.95 it would be the 5 that I need to change. I need and final digit to turn into a 9. The example from before would have to look like $7.99 after I plug in the statement. I created an if then statement which would technically work and I attached, but I don't know how to properly represent the monetary value that I'm not trying to change and the formula is really bulky. Would love to know how to represent the changing dollar and cent amounts properly and some tips on how to make the formula look better. Thanks so much!