What do the stores do with all the five cent deposits they collect if the bottles aren't returned?

Each State, that participates in a bottle return program, has its own bottle return laws and legislation. New York for example, has the New York State Returnable Container Act...and laws under Dealers Return.

How Does the Deposit System Work?
Distribution Chain at a Glance
BOTTLERS/BREWERS
label containers
charge deposit on refillables only
DISTRIBUTORS
first to charge deposit for nonrefillables
RETAILERS
pay deposit to distributor
charge deposit to consumers who take container away
CONSUMERS
pay deposit

Redemption Chain at a Glance
CONSUMERS
return containers to dealers or redemption centers
collect deposits
DEALERS
return deposits to consumers
sort containers for distributor pickup or send containers to redemption centers for sorting
collect deposit plus 2 cent handling fee
REDEMPTION CENTERS
can serve as sorting services and/or recyclers
work out arrangements with distributors and dealers for sorting, recycling, and payment system
DISTRIBUTORS
collect containers from retailers and redemption centers
pay deposit plus 2 cent handling fee on containers
may arrange with redemption centers to recycle materials
BOTTLERS/BREWERS
get back refillable containers only

For bottle deposits that are collected by the retailer, for bottles that aren't returned by the consumer, you would think that the program would be a loss for the retailer...or "dealer"...they do receive 2cents for every bottle return--maintance for machines, people working the bins and accounting costs--...and in regard to the distributor, by law:

Distributors charge a deposit when they sell beverages to retailers. However, a distributor who manufactures beverages but does not sell to retailers is not allowed to charge a deposit except on refillable containers. This refers specifically to the beer industry where brewers sell to distributors who sell to retailers. The brewer may not charge a deposit except on refillables. In the soft drink industry, the bottler and distributor are usually the same; therefore, this distinction is usually not relevant. For imported beverages, the first U.S. distributor is responsible for initiating the deposit.

The distributor is the one who really makes out, if at all, in regard to bottle return, but...there are a lot of costs asscociated with collection and recycling. If the consumer doesn't return the bottles...the consumer is obviously loosing money. Bottle return money needs to be accounted for and kept tabs on...the retailer "dealer" has already PAID for the deposit. They are just passing it to the consumer. The 'dealer' will not get the 2cents per bottle, if a bottle is not returned.

If you want to know more about this...and how much money distributors collect and make in regard to bottle returns, your best bet is to further research recycling center costs..and distributor costs assoctiated with this.