The following shows steps to introducing the concept of the value of money and of adding coins.
The concept of a dime is presented as 10 pennies (see below). The dime is compared to a penny, nickel and quarter using these representations. Repeated use of these representations leads into an intuitive understanding of the coins.
Next is determining the value of multiple coins. The place to start is with pennies, which is relatively easy as the number of pennies represents the value. The next step is to count dimes because counting by 10s is relatively easier than counting by 5s or 25s.
Dr. Russell Gersten is a guru in special ed. At a presentation at the 2013 national Council for Exceptional Children he explained that number sense is best developed using the number line. With this in mind I created a CRA approach using the number line.
First, the student lines up the dimes on the number line (see photo below) then skip counts to determine the cardinal value, which is the value of the coins. 
Upon demonstrating mastery of counting dimes, the student moves from using coins (concrete) to a representation – see photo below.
This approach is used for nickels and then a combination of nickels and dimes (corresponding blog post forthcoming).