Welcome to the forum!
To help set expectations, #1 as suggested above is true 99.9% of the time, common coins with very little numismatic value. How many coins are we talking about? There is a time cost in going through boxes/jars of coins (for you and for the dealer) and they have no reason to invest their time unless they can make a profit.
If you want to invest your time, itemize each coin by specific series, date, and mint mark. If you don't want to commit that level of time, at least identify each coin group by series on a list (i.e Washington quarters, Morgan dollars, Mercury dimes, etc.) and share here. We can quickly tell you what to look for. Those new to coin collecting and value are often shocked to learn 100 year old coins can be worth pennies over their face value for example. For example, a normally worn 1955 penny could be worth 2-3 cents but the same coin if the double die error could be worth $1000.
It would be awesome if you really had something of value!