One little feature I loved in Quicken Classic was the “distribute proportionately” button when entering receipts on a transaction.
For example, if you had .97 cents left, you could click a button and distribute the amount proportionally between all the existing splits. More expensive splits got more of the leftover distributed to them. As it stands now, you just have to create a new split for Sales Tax and click the “Add Left to Split.” I suggest adding a second blue text on white background option.