No, it’s not alright, and it does NOT save any gas.
None. Zip. Zero. Zilch. Nada.
In fact, if your car is fairly new it uses MORE gas in neutral than it would if you left it in gear. Modern cars are programmed to shut off the fuel injectors under these conditions, so you use ZERO gas in gear but some gas in neutral.
In addition, coasting downhill in neutral is dangerous.
I advise you to stop this practice.
Fill the gas tank before it gets that low.