Validation of data with checksum vs Binary_checksum
The solution that helped me solve this dilemma was to use the hashbytes with SHA2_256 which was then converted to a bigint followed by a conversion to a float to finally be summed up.

Note that the conversion from varbinary to bigint can be dangerous, but in my case it was acceptable.  the conversion directly from varbinary to float is not supported... and to sum up many records with a bigint wasn't enough due to an overflow... hence the reason to convert the bigint to a float.