The negatives here are the ones used for facts, which are not commonly used with prohibitions. The Mark and Luke versions of this verse use the other Greek negative, that has the sense of not wanting to do something. Jesus does use this negative in the prohibitions in the Sermon on the Mount, Matthew 5:21, Matthew 5:27, but their the used is somewhat exaggerated, for the sake of humor. 

The forms of the verb are subjective, not commands, something that "should" or "might" be done. Note both KJV and NIV get this correct but use the confusing "shalt/shall" construction which is confused with the future tense, which these statements actually could be grammatically because these verb forms could be either the future indicative or the aorist (a tense meaning "at some time") subjunctive. Logically, however, these are not statements about the future but statements about what you should do at any time. Some Bibles show this as commands, which they aren't. Others show them as "must" statements, which they are not.

This verse is much pithier in Greek, two words, a "no" followed by the verb, but to capture all the information in the negative form and the verb, we would have to say something like: "No, you really shouldn't murder at any time." The Mark or Luke versions with the negative of opinion, say something like, "No, you shouldn't want to murder at any time."