Round UP for Cut Materials

Hi folks,


I need to a help to round up or down (depend on the number) all the numbers different than 150,200,250,300,450, 600 on the collums E and F
Also, use these new values on the formula =COUNTIF(E4:E11,"300") to show how many of these numbers I have on E8.
per example: on E10 i have 340 and I`d like to change this number to 450, only to use 450 to count on I9,
the problem is that I dont wanna show the round up value on E10, i wanna keep same.

to clarify we have this na, pa sizes standarts 150,200,250,300,450,600. When we have an order that require us to cut these material we do but we need to deduct from the standart size.




thanks in advance