We don't have synonyms for stiver yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are sliver, shiver and striver.
(n) :
a small Dutch coin worth one twentieth of a guilder; anything of small value
"1761: 'Tis not worth a single stiver, said the bandy-leg'd drummer -- Laurence Sterne, The Life & Opinions of Tristram Shandy, Gentleman, vol. 4 (Penguin 2003, p. 223)"
(n) :
a small Dutch coin worth one twentieth of a guilder; anything of small value
"1761: 'Tis not worth a single stiver, said the bandy-leg'd drummer -- Laurence Sterne, The Life & Opinions of Tristram Shandy, Gentleman, vol. 4 (Penguin 2003, p. 223)"