How do I get across the River Styx?

Hint 1 of 6:

Have you found Charon yet?

Hint 2 of 6:

Knowing something about Greek/Roman mythology helps here.

Hint 3 of 6:

Dead souls need money to pay their passage across the river.

Hint 4 of 6:

Someone in the game was buried with money on him/her.