Say for example you started with $200. Now you dont want to stick that down on 1 spin, it is too risky. It is much better to split that down into say 20 x $10. And then on each spin place 20x50 cent bets (total $10). Then if you start hitting some numbers/splits etc then you can increase it, but conversely if you start missing lots you can decrease it.

To illustrate:
Bet $10 (50c on 20 splits) - hit 1, win $9, BR now $199
Bet $10 (50c on 20 splits) - hit 3, win $27, BR now $216
Bet $12 (50c on 24 splits) - miss all, lose $12, BR now $204
Bet $10 (50 on 20 splits) - miss all, lose $10, BR now $194
Bet $9 (50c on 18 splits) - hit 2, win $18, BR now $205
etc

As you see you are tailoring the bets in relation to our bankroll (BR) size. Whilst this example isnt exactly 5%, if you think about it as 5% of your bankroll then I am sure you'll get the idea. If your BR decreases to $100 you might want to change to 25c chips and still place 20 of them, or if it went up to $300 then you might want to increase the bets to $15 total per spin.