Retailers
Are of course the same as anybody else:
Some are honest and some are not.
Sooner or later all will make mistakes, some people will make more mistakes and more often than others.
All are curious, some more than others.
Some are nicer than others and some are not nice at all.
If they notice that you win often, some will of course try to copy your numbers, they would be crazy not to.
So if you happen to win often, perhaps it might be best to buy and cash tickets at more than one place, buy at some stores and cash at others, but rotate them.
Get to know the clerks and only buy and cash tickets with those clerks that you trust.
Most clerks will never copy your numbers unless they notice that you are winning, they run too many tickets thru the lottery terminals everyday and can't afford to buy too many numbers everyday.
Do check your numbers and tickets before and after you buy them.
Do try to be polite with the clerks if possible, but make sure that you do get what you paid for and also check your change before you depart from the store.
If a clerk prints a ticket 2 times by mistake, the extra ticket will either be sold to somebody, bought by one of the clerks or kept by the store if it can't be sold.
With tickets won and with free promotional tickets you have to be EXTRA careful, some clerks like to keep those "Free" tickets or at least some of them.
Good luck!