`round` method is not functional

[tomsail]

The round variable is not used in the round function:

https://github.com/oceanmodeling/seastats/blob/bda9c00cc485e573953e5de53c147094b365b2e9/seastats/__init__.py#L189C14-L189C15

[pmav99]

Please add a test