How big/expensive a container are we talking?
First of all, I wouldn't just accept your boss saying that. Does your contract mention the company recouping cost from your salary and how is it decided what amount should be deducted? He/she shouldn't be able to just make snap decisions like that, and if they are, they should at least have the respectability to go about keeping back salary properly and working out the actual cost of 'damages to the company.' Even then, really, a jar of guacamole? Recouping the cost of that is honestly pathetic. Unless the guacamole was made out of platinum then your boss is being unkind to charge you for what I assume to be a genuine accident.
Secondly, I'm extremely sorry this is making you feel crappy. I hope it all resolves itself in the end.
If you don't mind me asking- what is the rest of your job like? I'm just wondering if perhaps your boss takes too much advantage of employees or isn't fair a lot of the time.