How do I enter a T5 that has income for both my wife & myself? does it have to be entered on both returns with the appropriate %?

You can enter it in one return and specify the percentage.  For example, if you and your wife have a T5 which has $200 in box 13 (interest from Canadian source), in Forms mode T5 slip, you can enter 50% (or any appropriate %) for your percentage and 200 in box 13.  TurboTax will calculate your spouse's percentage and divide the $200 accordingly.  In this example, $100 each.  You can check it in T1 General, line 121 (or schedule 4).