Count Line Items Based on Date

I have a workbook that has five worksheets in it, each representing a different salesperson. Each of these worksheets contains three columns: the date, an item description, and the number of items sold. What I would like to do is add a sixth worksheet that tallies up the total number of items sold each date.

I've attached a workbook as an example, in which I would like to have the total number of items sold by the three salesman displayed in the appropriate date columns on the "Totals" sheet.

Any help would be greatly appreciated.