Hello Thrustman1,
Given that your camera doesn't allow RAW shooting, images will be stored in .JPG format. It's important to understand that the JPGs are already compressed in-camera (the degree of compression varies from camera to camera, but typically greater for "point & shoot" cameras).
Exporting your original JPGs as .PNG or .TIFF will not improve image quality, but it will ensure maximum quality is maintained (i.e. no further compression). As you're aware, it affects file size significantly.
Like tomasc, I would usually export as .PNG or 100% quality .JPG. I would only use .TIFF if my intention was to further edit in other software, which is rare.
PIX
PIX YouTube channel