problem with using tiles

in my game i am using tiles by scaling the screen size

so pixels are now like 4cm
picture1.scale(1,1)-(10,10)

any way what happens is when i make the picture1.width smaller or the picture1.height smaller so do the tiles.

i want the tiles to stay the same size no matter how big or small i put the width and height

does anyone know how to do this, or if they know a better tiling method?