The Torah commands us to refrain from possession of the trappings and tools of the trickster's trade. We may not have in our pockets two different weights (Devarim 25:13) nor in our house, two different dry measures ( Ibid 25:14).
The Torah then emphasizes that we must own proper, just weights and containers for dry measure. And to cap it all off – if we abide by these guidelines (required, not suggested) we will merit long life (Ibid 25:15).
There seems to be much more being discussed here.
Firstly, we are already under "standing orders" not to cheat in business or in any way swindle our fellow man. Secondly, even if we were to view this commandment as an expansion upon the concept of honesty (since previous laws focused on the practice of cheating and this one prohibits mere possession of cheating paraphernalia), we still must question the insistence of the Torah that we acquire proper weights and measures. Supposing I want to refrain from weighing and measuring altogether – shouldn't I be within my rights to forgo the entire experience – why must G-d insist that I possess accurate tools ?
Because these laws are alluding to a much bigger issue. Not everyone is involved in the buying and selling aspects of business. We do all make purchases from time to time – so the simple, literal meaning of this law certainly applies to everyone. But, this law can also be seen as referring to a different system of weights and measures.
We each make dozens of decisions daily. We weigh our options and measure our resources – in an attempt to "get the best deal" towards whichever goal we are working for.
The Torah is cautioning us – it is not sufficient to engage in honest self assessment when pursuing our life's goals. We must purge our value system of dishonest considerations completely ! It is not enough to avoid rationalizations and other mental manipulations when serving G-d – we must eliminate these things from our lexicon entirely!
In this month of tremendous divine assistance in our personal betterment – may we merit this, and all other, lofty steps in pursuit of our ultimate goal. As Dovid HaMelech said – "… To sit in the house of Hashem all the days of our life " [Tehillim 27:4]