Welcome to the Board!
Try:
=if(a1<.88,0,if(a1<.9,1000,if(a1<.92,1250,1500)))
or:
=if(a1>=.92,1500,if(a1>=.9,1250,if(a1>=.88,1000,0)))
You can also use lookup or vlookup for this, but I have to go and this was easier for me to type out.
Hope that helps.