If you discount based on card colors, this is the default setup in Rose. There's nothing you need to do except to set the default card color for new inventory within the Locations Module, which can be found within the Hamburger Menu.
Setup your default Take-In card color for your location and Save. If you do this monthly or bi-weekly, set yourself a reminder to change this in Rose when the time comes to do so.
When you are read to discount a particular color, set the discount to the new price %. If you want a 20% discount, set the price to 80 and then click the button [COLOR] UPDATE SQUARE. This will send all inventory attached to that color with the new discounted price to Square, so that they ring up at the new price at the register. Depending on the number of items in inventory this can take from a few minutes to a couple hours. This depends on how busy Square is at the time so we suggest that card color discount changes be done the night before you want to put them on sale.