Formula for - Reward increasing once certain level hit

[dazles]

After a bit of help, need to do a formula where, once the total hits a certain level the rate increases. So I pay a company $50 on the first 1000 sales, then all sales after that are paid $100. Need a running total of $’s earned.

Any help appreciated

[#2]

If your cumulative sales start in A2 and your payments start in B2, the formula in B2, copied down rows, is:
=LOOKUP(A2,
{0,1000},
{0,50}+(A2>1000)*100)

[#3]

Many thanks @Twifoo 

[#4]

Welcome.