I looked it over and here is what I can make of it.
Oct. 5 1875
Mess (Abbr. for Messrs. pl. for Mister) Fuller & Parrish
Norwich, Conn.
1 oct (Octagon) rifle 44/32 (.44-77 cal. + 32"barrel length)
S of rs WG & Singl. (presumably single-set trigger but the rest looks like company jargon that a Sharps clerk would better understand)
less of 20% (20% discount)
(Math calculation of $75 minus 20% being $60.00)
50 Shells $1.32 less 15% (calculates to $1.13)
1 Box (for rifle) $ 0.75
$61.88 + .50 (shipping?) $62.38
Shipped this day.
(Clerk signature)
Have a look at this link to the Zimmerman Sharps documented to Dodge City. With the exception of the double-set triggers, this is the same gun,
https://absarokaantiquearms.com/product/hartford-sharps-sporting-rifle-model-1874-shipped-to-dodge-city-kansas/