It appears that PayPal does not support pricing in RUB, but 2CheckOut can; this help page explains how to integrate 2CO with E-junkie:
Note that 2CO cannot support our Cart buttons, so you would be limited to using our Buy Now buttons for 2CO, which means you could not use our cart-dependent features such as shipping/tax calculation, items using Variants/Variations, or many types of discount:
Also, adding a RUB currency option to Seller Admin would need to wait for the next version of Seller Admin we've been working on, so I'll put that request on our wishlist to make sure Development is aware of it. Meanwhile, it looks like we should be able to set your products' pricing currency to RUB for you by modifying the product records in our database manually. The catch to this is that you won't be able to edit your product settings after we do this -- well, technically you could, but it would result in the edited product becoming un-orderable until we re-add the RUB currency setting manually again. We can apply this currency setting for your initial setup and to fix the occasional need to edit a product, but we cannot feasibly offer to extend this favor on a routine or ongoing basis.
If this would be acceptable to you until our new Seller Admin is ready, go ahead and set up your products and test with USD, then let us know when you're ready to have them changed to RUB.