All =1000000000 nxt; //10b
Ab =account balance;
Case one: Similar 1 nxt = 1 vote
if Ab<=1000; {1 nxt = 1 Vote;} // no fee ,if set fee,the fee will be obtain by large shareholder.
if Ab>1000 and Ab<=10000; {1 nxt =(1-Ab/All) vote;}
if Ab>10000 and Ab<=100000; {1 nxt =(1-Ab/All) vote; and min fee=1}
if Ab>100000 and Ab<=1000000; {1 nxt =(1-Ab/All) vote; and fee= (Ab/All)*10000;} //max fee= 10nxt
if Ab>1000000 and Ab<=10000000; {1 nxt =(1-Ab/All) vote; and fee= (Ab/All)*20000;} //max fee= 200nxt
if Ab>10000000 and Ab<=100000000; {1 nxt =(1-Ab/All) vote; and fee= (Ab/All)*20000;}//max fee= 2000nxt
if Ab>100000000; {1 nxt =(1-Ab/All)vote; and fee= (Ab/All)*35000;}//max fee= 3500nxt
But:
Maybe a person owns 100,000,000 ( e.g: [10000 accounts * 10000 per account] or [100000 accounts * 1000 per account] ) , do you have better good idea?
Case two: Similar 1 account = 1 vote , No matter how much the amount, fixed amount of voting.
if Ab<1000; {1 account = 0 vote; fee=1 nxt} //acct less than 1000, no the vote right.
if Ab>1000 and Ab<=10000; {1 account = 1 vote; fee=1 nxt}
if Ab>10000 and Ab<=100000; {1 account = 1 vote; fee=1 nxt}
....
.....
if Ab>100000000; {1 account = 1 vote; fee=1 nxt}
In this case, the account count is limited, because
each must have nxt amount over 1000.
Maximum number of accounts is 1,000,000,000/1000 =1,000,000 vote
E.g:
if a person owns 100,000,000 ( e.g: [100000 accounts * 1000 per account] ) , He Max gets 100000 votes, this is a POS system, which is his right, and he will pay more than 100000 fee. Difficult?

But this system is not the minority game, so a large number of small shareholders have a right to vote too...
100000 people each owns 1000, will beyond him... Difficult?

So if you want to win the vote, or pay fee >100000 Nxt, or to find >100000 people ( >100000 accounts)
Edit: Case two Add a condition: Block Limit.