2 percentage discount in one cell

[TRIPLESIX]

Hey all,
We are trying to create a worksheet for some pre-ordering to be sent out to our customers.
In the worksheet there will be items for sale that our customers can order but we are trying to work in a price break for quantity.
For example: if a store buys 0-10 items in total, they get no discount, if they buy 10-15 in total they get a 3% discount and if they buy 15 or more they get a 5% discount.
We want these totals to be taken off the total price of the items ordered.

I worked out using the below formats that i can get either 3% or 5% to come off the total and show both separated by a "-" but we need it to have one of the other in the cell depending on what is needed.
=SUM(D5:D9)*(IF(C10>=10,-0.03)) - for 3% - D5:D9 is each items individual totals added up to give the total before discount. C10 is the total quantity of items ordered
=SUM(D5:D9)*(IF(C10>=15,-0.05)) - for 5%

I tried to combine the 2 with the below format but it's showing both(see cell D12) but i need it to only show one of the other or none if no discount is applied.
=SUM(D5:D9)*(IF(C10>=10,-0.03))&SUM(D5:D9)*(IF(C10>=15,-0.05))
I have attached a pictures which hopefully helps.
Thanks.
Screen shot 2015-01-29 at 5.05.09 PM.png

[samba_ravi]

Try this
=SUM(D5:D9)*LOOKUP(C10,{0,10,15},{0,97,95}%)
or
=SUM(D5:D9)*(1-LOOKUP(C10,{0,10,15},{0,3,5}%))

[TRIPLESIX]

Yes, that worked perfectly. thank you so much.
I spent hours trying to work that out, i should have just came here straight away.
Thanks again, much appreciated.