increasing resolution quality of a jpeg

Right, it's time for Inkscape 101.

There are two types of image files: raster; and vector.

Vector images (the kind Inkscape specialises in) are constructed from mathematical principles. They can be scaled to any size because, essentially, it just means changing a number for multiplication. They are, therefore, resolution independent. SVG (Scalable Vector Graphics) images fall into this category.

Raster images (also known as bitmaps) are created from a grid of pixels, just like a mosaic, except that the tiles (pixels) are tiny. The size of the pixels determines the resolution (the maximum amount of detail) of the image. When scaling up, clever algorithms try to interpolate the colour data to avoid blockiness by filling in with an average of the surrounding pixels. But they can't just find details that weren't in the original image; it's just an attempt to smooth out the image and keep it looking something like a photo rather than an ancient mosaic. JPEG images are raster images.

While you can trace a bitmap to create a vector image (e.g. SVG) based on a raster image (such as a JPEG), no extra detail is added by this process, just as no extra detail is added by the scaling algorithms. The vector image is freely scalable, but the image it's based on will always have a fixed resolution.

So, no, you can't increase the resolution of a JPEG image (with any application). It is fixed. You can, however, try using a raster image editor—such as GIMP—to scale the image up. As I mentioned, the scaling algorithms are clever, and can be good enough to create a larger image with a reasonable appearance (almost as if it had a higher resolution—the illusion may be sufficient for your needs).