NEC 430.52(C)(1)

[skyline77]

Exception No. 1 says
When the value found does not match a standard size, the Code permits the next higher STANDARD size for a branch circuit overcurrent device
This is understood,

I didn't understand:
that does not exceed the next higher standard ampere rating shall be permitted.

Say I got the OC rating 440 A, since it's not a standard I round it up to 450 A, the NEXT higher standard size is 500 A.

Does it mean I should not exceed 500A?
How would I exceed 500 if I selected 450A which is the next higher standard size per the calculation!

I am confused

 

[infinity]

If your calculation comes up with 440 amps, which is not a standard size, you may go up to the next standard size which is 450 amp in Table 240.6(A). Not sure why you are "rounding up".