From the legal discussion website linked below:
"You are not qualified to know whether you are innocent of wrongdoing under federal criminal law."
From the article:
"If you are not in custody, your total silence, especially in the face of an accusation, can very possibly be used against you as an adoptive admission under the Federal Rules of Evidence.
The Supreme Court hasn't been very friendly about silence - in and of itself - being enough to affirm your rights
but really the article focuses on someone selected for questioning... not a random guy stopped when exiting a provider's location.
If you discover you are in the former group, it would be very wise to heed this advise & consult council before giving any information or making any statement beyond identifying yourself. Never Ever make statements from recollection that will subsequently be picked apart by someone with all the time in the world & records available to them... who will make you appear a liar because of minor & insignificant discrepencies.
If, on the other hand, you are randomly stopped by Police & asked for information... You were just the one they stopped... they don't even know who you are (yet). In most states you are required to identify yourself. Beyond that, I'd advise to decline to answer questions & immediately ask if you are being detained. They shouldn't have cause to detain you but will if you keep talking. If you are being detained, ask for council.
I would add, ask for counsel and then stop talking. They are supposed to stop questioning you once you've asked for counsel. If you start talking again on your own after you've asked for counsel, you may implicitly waive your Miranda rights.
http://www.nolo.com/legal-encyclopedia/questioning-after-claiming-miranda.html