How is rounding to the nearest thousand done for Optional Life insurance rates?

We are seeing some discrepancies with how PeopleSoft is rounding the salary to the nearest thousand. Many situations - it appears to be rounding up, even though the dollar amount is clearly below the $500 line. For example, it will round 35,450 to 36,000.

There are other occasions where it rounds down. For example, it rounded 95,017.00 down to 95,000.

We use the Age Graded Rate table for the Optional Life rate.

Is there any document that explains what PeopleSoft is doing?

Thanks!