403b splitting match between pre and roth

Currently, we have our 403b set up if you put all your 5% in pre you get the full match. Next year they are looking to allow you to split out the match so if you want to put 3% in Pre and 2% in Roth you can still get the full match. We just went live in January with Calc Cards where our 403b is set up. We figured out how to add the Roth Element and Calc cards but does anyone have a fast formula or suggestion on how to split out the match? Thanks