Percentage query, actual commission at stake, please educate me

Thank you in advance to anyone who can give me the answer.

Please can someone out there help me, I have had 10 views but no replies?

My sales commission is paid out against a muliplier from an average percentage achieved in all customer surveys received, which were scored from zero to 5.

Multiplier A = 97%+, Multiplier B = 95%-96.9%, Multiplier C = 90%-94.9%, Multiplier D = less than 90%

The structure of the customer scores against equivilant percentage has now changed

Old Structure:...............New Structure:
5/5 = 100%.................5/5 = 100%
4/5 = 80%..................4/5 = 50%
3/5 = 60%..................3/5 = 0%
2/5 = 40%..................2/5 = -50%
1/5 =20%...................1/5 = -100%
0/5 = 0%

Can someone please tell me what the percentages/ranges should now be equated to for Mulipliers A, B, C and D.

As the bosses are still "deciding", (ie they don't know how to work it out mathematically either) and I dont want to end up short changed!