Heck yah!!
I usually ask as I have the boxes, and ready to walk out the door, "does you guys have any loose halves also?"
Last week, I ran into a buddy from work at my pickup bank, picking up 6 boxes... he knows what I do and he sometimes hunts dimes/nickels for silver... He said he was going to go inside and ask for silver, and I told him I had to go get my other 3 boxes that I paid for, and on my way out with my last 3 boxes, I asked "Do you guys have any loose halves?" And no one said anything till I was about out the door, and one teller said she had 1 coin... so i set down my 3 boxes and walk over, and exchange 2 quarters for a 67 half! haha... I walked out the door and flipped it to him to see what he missed out on! haha
Honestly I feel more weird asking my dump banks if they have any halves, after they just cash me out for 1k+ of halves... lol, but they dont seem to mind at all, and last week I scored 9 40%ers out of $5.50 in a teller tray at the one dump bank.