I know of no way to turn off deleted items reconciliation when using Exchange ActiveSync, since any ActiveSync function is a true synchronization of the integrated exchange account. With BlackBerry, there's a setting on the device itself that allows you to turn deleted items reconciliation off, but remember that BlackBerry devices always use their own server (be it BES for Exchange or BIS for OWA) to connect your device to a third party server, so there is room for little customizations here and there. With an ActiveSync, the device communicates directly with the Exchange server, and as far as I can see, there's no way to bypass its native functions.
If you go into Settings - Mail, Contacts, Calendars - select your work account and go into advanced settings, you can experiment with settings, but I'm not sure you'll be satisfied. But given I don't have an Exchange a count configured, I could be wrong about its capabilities.
