In most cases, dealers don't do trades as such. They will buy your dimes and sell you half-dollars and dollars. Each transaction has a bid/ask spread as he expects to make a profit on every transaction. Look at the bid and ask numbers for each type of silver coin before you do the swap. That will tell you how much profit he expects. In general, the larger coins are quoted higher than the dimes and silver war-nickels. All quotes are based on the silver content, of course.

If you are buying and holding to be sure you have something to barter when US currency is worth nothing, keep the dimes. That way you won't have to accept change in silver-less coins when you buy a bar of soap or loaf of bread. Remember that even worn and scratched silver dollars will sell for $20-30 these days.

You might do better to offer some of your silver dimes in exchange for larger silver coins at flea markets or antique shops if that's the trade you're trying to arrange. You can give them the argument about emergency money in smaller increments being often desirable.

I keep my emergency money in silver dimes and quarters myself and have for 40+ years.