I haven't crossed since the new bridge but I don't think there is a toll fee - for cars at least - there may well be for lorries. Plus remember there is a ferry (c.$30) if you come via Kazungula.
I don't know which direction you're traveling but generally speaking entering Namibia is a doddle, Zambia less so as there are a range of different taxes/ fees to pay or docs to deal with - visa, TIP or carnet, carbon tax, insurance, road tax and council tax. But Sesheke is much more low key than Kazungula where you have to beat off the fixers.
BTW - V IMPORTANT if you are entering Zambia make sure you get something like "all over Zambia" endorsed on your road tax. It is supposed to show your "destination" in Zambia but if you just put a town the police will try and fine you as soon as you appear to be heading in a different direction. It costs $20 regardless of what goes on it.