We had similar issues and went through many settings to get large files to upload. We are using a custom web service to do the upload, so there was an extra setting to update in the web.config file of the web service. Here are all of the settings we updated to get past the 5 MB limit:
IIS Setting in IIS 7.0:
IIS 7.0 Manager
Go to SharePoint:80 (or Whatever one you are using...)
Click on ASP (Under IIS Section)
Double-Click on ‘Request Filtering’
Click on ‘Edit Feature Settings’ from right side under ‘Actions’
Check ‘Maximum allowed content length’ to be > 50 MB
Set to = “53000000”
IIS 7.0 Manager
Go to SharePoint:80 (We also had to update this setting for our webservice)
Click on ASP (Under IIS Section)
Click on ‘Open Feature’ from right side under ‘Actions’
Expand Limits Properties section
Check “Maximum Requesting Entity Body Limit:” setting. Should be larger than largest file size:
Set to = “53000000”
ASP.NET HTTP Setting:
Setting I added to web.config of webservice for 50MB limit and increase the time out:
<system.web>
<httpRuntime executionTimeout="300" maxRequestLength="51200"/>
InfoPath Specific Setting:
SharePoint Central Admin -> Application Management
Click on "Configure InfoPath Forms Services" under “InfoPath Forms Services “
Check the “Maximum size of form session state”. It should be set to allow for large file attachments – 50 MB or larger.
Set to = "53000"
I hope this helps someone else.