If formula to return blank if reference cell blank

I have set an IF formula to return a value of 1 to 5 based in the % range of the reference cell however, if the reference cell is blank I need the formula to return blank

This the the formula i'm using =IF(N3<=0.0075,"1",IF(N3<=0.0099,"2",IF(N3<=0.0124,"3",IF(N3<=0.0149,"4","5"))))

Any help would be great

Thanks
Donna

Thanks so much davesexcel works perfectly