Generally when guys ask girls to dance they mean grind, so its unlikely if you have just met her she will - you are basically offering her a ride on your possibly infested jeans.
Here's how it COULD work; catch eye contact - do a stupid dance movement directly to her, then if she giggles ask her to dance non verbally with the hand of god (just hold out your hand) if she's into it she'll take it, no resistance. If she's not you ignore her and carry on. General idea is to get a non verbal response more often than not- like a smile or a giggle, by dancing stupidly you show you are not a threat, you take her hand, spin her, maybe do one more ridiculous move to make her comfortable when she is dancing with you, then ESCALATE. (you said you're a decent dancer -me too - I do a little body popping in front of them, hand of god, and then say "wanna learn a little something?

")
Take her hand and show her how to pop and lock a bit, spin her into a grind and see if she resists or goes with it, if she doesn't seem into it, spin her back round and DROP her hand. To everyone else it will look like you got rid of her, and you have been dancing with this girl. Even if it goes well and she enjoys it, make sure you are the one to end it, not her. It shows you are in control and don't need her to validate you by dancing with you.
Hope this helps,
Jake