$10 off Origin purchase code

I don't think so, you buy DLC via BioWare Points which you in turn can buy on Origin, but I think these promo codes only work for Games, not points. You can of course try though  just put the BioWare Points in your shopping cart, apply the code and see if it is accepted.

just use the search function of the shop and search for "bioware points". You can then put either 800 points or 1600 in your shopping cart. And then you can try if your code works.

I tried with adding the 20$ (1600 points) and didn't work. Probably because it's not a game as you mentioned.

I tried my luck by adding a with a 19.99$ or less game in the cart and didn't work either.  

That confirm you can only buy games of 20$ or more. Thanks for your help!

The 5X10$ promo code offer was a bonus for pre-ordering SimCity Digital Deluxe. Current offer is 1X20$.