Step cart quantity 6,12,18,24,…

Hey. I have preorder question: I need this plugin to control minimum order quantity for all orders in my shop and define step order quanity. To explain better: Unless there are not 6 products from my store in the cart, it blocks user to complete purchase and remind him to add more products. I need also step order quantity, so only 6,12,18,24,30,…. products can be purchased. 1st example: someone add 1 product in cart, it reminds him to add 5 more. 2nd example: someone add 8 products in cart, it reminds user to add 4 products in cart (so quantity step is 6,12,18,24,30). Please let me know if it give me that solution.