Can Inventory show a $ total for all items in my database?

Inventory doesn't currently contain an option for showing a current value for all stock, however, you can calculate a total using Excel.

To export the data in your Inventory database, click on the "File" menu and select "Export Records". In the export dialog window, select "Entire Database" under Records and leave the Format set to "Tab-Delimited". Next, check off the fields you want to export (quantity, price, etc.), then click the "Export" button.

The tab-delimited text file you create can be opened in Excel and the sum function in Excel can be used to calculate a grand total for you.