You can never have too many plastic containers. But they do have a tendency to absorb the smell of whatever you store in them long after discarding and even washing. So here's a neat trick: throw some paper into it.
The One Pot Chef says that for any plastic container which has the smell of whatever was stored in it -- like a sauce -- clean it thoroughly and put some scrunched up newspaper or other paper in it. Newspaper is apparently a magical deodoriser, even removing bad smells from shoes and fridges. Seal it up tight and store it as usual. The next time you want to use it, remove the paper and rinse it for an odour-free container.
Quick Tips: Removing Odours from Plastic Containers [The One Pot Chef]