How to read XML output using PHP

I am trying to read an XML output listed below

SimpleXMLElement Object ( [merchant] => SimpleXMLElement Object ( [merchant-id] => SimpleXMLElement Object ( ) [merchant-name] => Snip-Its [merchant-category] => Hair [merchant-website] => www.snipits.com )

[store] => SimpleXMLElement Object
    (
        [store-id] => 173DFBB7-67F6-DE11-AD5B-0026B953348A
        [store-name] => Heb
        [store-number] => 0109
    )

[coupon] => SimpleXMLElement Object
    (
        [coupon-id] => 385748
        [coupon-address] => 14096 Memorial Drive
        [coupon-city] => Houston
        [coupon-state] => TX
    )

)

using PHP script as follows but I get a value of '0'

foreach( $data->coupons as $mycoupon ) {    
      $address = $mycoupon->coupon->coupon-address;     
    //print_r($mycoupon); 
}

So, Please help me to understand how to read the values of SimpleXMLElement Object and assign them to a local variable.