Gocoin.com, they provide extensions for almost all major CMS.You can accept bitcoin,litecoin, and dash.
Whenever a client wants to accept altcoins, I use this.Never had a problem, but some of their extensions are old and haven't received any update for over 3 years.

You can also try selly's extension https://github.com/Selly/selly-woocommerce
If your website is build on wordpress.
Or you can use their API.

Good luck!