Drop-In Discounts - Different Levels

I want to give dance professionals a discount. Currently our drop-in rates are

$15 for 45 minutes
$20 for 60 minutes
$25 for 90 minutes

We would like to offer the following:

$10 for 45 minutes
$15 for 60 minutes
$20 for 90 minutes

How can we do that? When I look in drop-in settings, it is only one price!

Thank you!