Help with formula

[trfountain22]

I'm trying to input a zip code and the tax rate for that zip code auto calculate and then multiply that by the sub total. I'm not sure if it can be done behind the scenes. Would someone mind looking at it for me. I have the tax rate already populating based on what zip code is entered (I78) but can this be multiplied by the sub total and that value be returned instead of just returning the tax rate?

 

[Candyman8019]

Try: =IF(H78="","",(1+INDEX('Tax Rate'!$C$2:$C$2877,MATCH(H78,'Tax Rate'!$D$2:$D$2877,0)))*I77)