Tournament prizing algorithm

Produce a formula that calculates a cash prize distribution among the top 60% team of the participants who entered into a contest.

For example:

Entry Fee for the contest is : 49INR or 49$
Total size of the contest is: 300000
So total winner will be: 180000. ( 60% of 300000 )

I need a formula that will distribute the winning amount into the 60 percent teams.

In the above case total winner are 1800000
Contest size is : 300000 so 300000*49 = 14700000INR
70-80% of this amount only be distributed to winners

In one of the competitor site in above case the prizes are
Prize 1: 5,00,000
Prize 2: 2,50,000
Prize 3: 1,00,000
Prize 4-4: 30,000
Prize 6-10: 10,000
Prize 11-50: 0,000
Prize 51-500: 2,000
Prize 501-5000: 200
Prize 5001-30000: 100
Prize 30001-60000: 72
Prize 60001-95000: 49
Prize 95001-180000: 19

Please let me know your thoughts on this.

NOTE: If the contest size is 300000 and only 250000 user is enter to contest then the prize structure will change automatically.

If there is tie even that also to be handled