No module named tkinter

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I am trying to use tkinter in my ROS environment but I am having some trouble getting it set up. I added it to my 'packages.xml' file like this

<buildtool_depend>catkin</buildtool_depend>
<build_depend>roscpp</build_depend>
<build_depend>rospy</build_depend>
<build_depend>std_msgs</build_depend>
<depend>python-tk</depend>
<build_export_depend>roscpp</build_export_depend>
<build_export_depend>rospy</build_export_depend>
<build_export_depend>std_msgs</build_export_depend>
<exec_depend>roscpp</exec_depend>
<exec_depend>rospy</exec_depend>
<exec_depend>std_msgs</exec_depend>

but when I install the package with 'rosdep install [my package]', the node I have 'import tkinter' in still will not run, and instead returns 'ImportError: No module named tkinter'. I am relatively new to ROS and have not installed third party packages before so I'm not sure if I'm missing something. Thanks in advance for any help!