Total Based Discount
You can offer depending on Total (Price) based Discount extension.
Admin feature settings:
1.Order Total and Amount (Like 100:10,200:12,300:13,400:15,9999:17).
2.Set discount type ( Like Fixed or Percentage)
3.Total depend (Like SubTotal or Total)
4.Payment Method(selected Payment method Apply Discount)
5.Customer Login
6.Date (between Start Date and Date)

How to Used
1. Log in to Admin
2. Find and Go to Extensions->Order Totals->Total Order Discount
3. Install and edit extension.
4. You can set rules
6. you can check discount in customer side.

Support
gmail : phpscript3@gmail.com
skype : phpscript31

Demo