Round *UP* to the nearest 100 in SQL Server

The following should work. After reading your question, I’m not exactly sure what you want 100 to return. For this 100 returns 100.

select floor((X + 99) / 100) * 100;

This gives the following results:

0 -> 0
1 -> 100
99 -> 100
100 -> 100
101 -> 200