Change prices on items - rounded up - magento shop

Need to highten all prices on items with a certain attribute with 10 percent, rounded up to nearest 4 or 9. Meaning every price should end with 4 or 9 to make them look better and avoid strange numbers. 94/99/104/109 and so on. Should also include prices for Custom Options (we use custom options for sizes since we make everything ourselves and dont need a specific stock number for each size). Meaning a product with a base price of 199 and an additional price of 50 for the next size should be turned into 199 x 1,1 (plus 10 percent), rounded up to 4/9 and the same done to 50. If ive made myself unclear please ask before giving a bid.