Context here is that, some number specified by a user is round up to some bits, like 1024, 2048, etc. so that it can make more sense for underlining cipher/hash algorithm.

In usual human calculation, we have 四舍五入. 1024 or 2048 things are computer things.

I refer to the Chinese document on hash algorithm, there are two operations：

1. fill some bits at the tail (for example, sha256 needs ((bits length) Mod 512) = 448) - 填充
2. and divide the fixed data into small pieces (for example, sha256 needs 1024-bit block) - 分组

And another adjective, if total length is a multiple of N bits, we can use 对齐(aligned、整列) to describe it.

舍入 is usually not used in bits operations.