Need help with GIMP for thumbnail creation.

I need a little help with GIMP for making thumbnails, and this seems like the most appropriate thread to ask about it. I have a very simple problem, I'm using images from The Binding of Isaac that are intentionally at a low resolution and whenever I scale them up GIMP tries to smooth it out and it becomes all blurry. I want to intentionally leave the image looking pixelated but make it bigger without it going all blurry. I hope I worded this correctly and posted this in the right thread.
Basically when you scale, GIMP does automatic antiliasing (smooths the edges out and tries to preserve the quality as best as it can). To scale and keep the original image, use image -> scale image -> set quality interpolation to none.