You can use the RunningSum property to calculate record-by-record or group-by-group totals in a report. Such a device is not available if you want to show a total on each page.

To sum an item per page, follow these steps:

Open the report in Design view.
On the View menu, click Code.
Create a module and type the following lines in the Declarations section:
Option Compare Database

Option Explicit

Public PageSum as Double

Enter the following code in the event procedure for the Print property of the detail section where <report name> is the name of your report, and <field name> is the name of the field you want to sum:
Private Sub Detail_Print(Cancel As Integer, PrintCount As Integer)

PageSum = PageSum + Reports![<report name>]![<field name>]

End Sub

Enter the following code in the event procedure for the Format property of the page header:
Private Sub PageHeader_Format(Cancel As Integer, FormatCount As Integer)

' reset the counter for each new page

PageSum = 0

End Sub

Insert a text box control with the following properties in the page footer:
Name: txtPageTotal

ControlSource: =[PageSum]

or

Private Sub PageFooterSection_Print(Cancel As Integer, PrintCount As Integer)
txtPageTotal = PageSum
End Sub

Run the report and note that the text box displays the sum of the relevant field for each page. If you want to simulate a running sum for the report, delete the reset line from the page header Format event.