Even the great
IrfanView can not make a partial pixel. A pixel is a "picture element" the smallest that you can divide something down to and still be able to call it that element.
Going up or down to the next whole pixel is not going to make any difference to your display. The display can not work with partial pixels either. It all depends upon if you want to size to be one pixel larger or smaller.
(NOTE: This in no way is saying that some software does not utilize some tricks of the display to 'clean' up some text display on the screen, to smooth out some sharp edges, as in what Microsoft ClearType does. In reality they are still working on whole pixels, just allowing the faint edges to be enhanced with the separate Red, Green, and Blue portions of any one pixel on a color display.)