I believe Ivans does but not sure about 3 Dives.

That sounds about right as far as cab fare from beach to west end for 2 with no stops.

The way I break it down is like this

2.50 each for the beach leg = $5
2.50 each for the west end leg = $5
Plus tip = $2
Add $1 or $2 if you make any quick stops along the way.

You can probably arrange a ride for $10 if you ask around or use the same driver frequently. I also wouldn't expect a private ride. If you specify you want a private ride then you may be looking at closer to $15 - $20.

As always prices are negotiable so it's really up to you and your driver to determine what works best but $10 is a very fair offer to start with and I usually never get turned down. If they ask for more I'll usually offer $12 and state that's including tip. Rarely do I get hustled for more and if I do I walk away and call or look for the next driver.