$5 is plenty for a reported balance. If you report smaller amounts, some banks will forgive the balance rather than bothering to bill you, and you'll be back to the all cards at zero penalty.
The amount that's forgiven can differ from bank to bank. Bank A might forgive balances under $1 while Bank B might forgive balances under $3. Rather than trying to keep track of the differences between banks, it's easier just to figure that $5 is a safe minimum.
The myFICO rep was correct when she said that 7% was a comfortable amount. Actually, anything up to 28.9% is going to be looked at favorably by lenders. But 28.9% will probably land you in the second best scoring tier.
The bottom line is that knowledge is power, and if you know why your score has changed, there's no reason to panic. If you don't like what you see, it's easy to fix the next time your card reports. 
@Anonymous wrote:
OK, that is good to know! So I can just use one for a small amount? That's good. Now that I've pulled myself away from it, I am good with using cash. I have zero balances here and am getting ready to pay my phone bill with one.
Let me ask you something real quick. You seen pretty knowledgable here...
I only have two cards total available credit around 2700. I was told by my financial advisor to apply for another.
I did and got pre approved for 3 from Amer Ex. I chose everyday blue.
This was in June.
They extended 4000.
I was told on this forum they don't report the card until the second statement.
A true fact because it's not appearing yet.
Is that card going to hurt me?
The hit for applying already applied
I think I got hit for like four points.
So now I am worried it will hurt somehow. My financial advisor assured me, it will help.
Anytime you have more credit available as long as you're not overextended, is a good thing.
Is that true?
Geez if fico hits me negatively for that, I wanna be prepared.
It will probably cost you some points in the short run but you will get them back quickly.
