Nevermind what is "right". I only wonder what the tool tasklist thinks, because it doesn't support outputting raw bytes -- only "K", such as "12 345 K".
I've stared at its help output for quite some time now. Also searched online.
Pretty much all of Windows and most major operating systems work with base-2 multiples so 1024-byte "K's". You can prove this with powershell where both KB and bytes can be shown under different output formats.
The only people who really use base-10 units for storage are the ones who have some vested interest in making their own numbers look better and everyone elses worse, just storage manufacturers.