I've got to hand it to the NoSQL teams. In some recent work on my EventStore project, I have seen how, when you give them a value to story and then query the associated document/row/whatever, the NoSQL solutions hand back the *exact same value* every single time. The RDBMS crowd is another story.
MySQL has an outstanding bug whereby it truncates any DateTime values and forgets the milliseconds on the value. Great. Oh, and the bug has been outstanding for *five years*. Ouch.
Access has some other, similar quirks. I'm not really sure if Access really deserves being mentioned with any other kind of persistence engine.
In contrast, when I give something to a NoSQL store, I can pretty much expect to get the same value back. At the same time, I should point out that in some cases, the default, client-side serialization for various storage engines may affect precision of some values, like dates and times. Even so, this is a limitation of the client-side serialization rather than the storage engine itself.