Show Incorrect Entry
To show incorrect entry specified as mutiples of 0.05 (0.05, 0.1, 0.15, 0.2 etc)
Use Conditional Formatting to select Formula is.
Then enter =ROUND((A2/0.05),0)<>A2/0.05 and Format as you like. If a number like 0.06 is entered, it will show as per the format you have selected.
Change multiples to suit.