You will have a cursor with one record for each amount. You init the cursor by CREATE CURSOR curAmounts ( yAmount Y) (eg you do that in form.load() event). You need to have a listbox and set it's Controlsource to "curAmounts". You need to have a textbox for the total named "TextboxTotal" and init it's Value with $0.00.
When you add an amount, you INSERT INTO cursorAmounts Values (newamount), you also add the new amount to the total in one textbox via TextboxTotal.Value = TextboxTotal.Value + newamount. Then just Refresh it via Thisform.Refresh().
The value newamount needs to be a numeric value, wherever that comes from. The cursor field type Y means it's a currencY field, so that is there to store prices or other monetary amounts, but you can also add "normal" numeric values to it, eg 1.00, all numeric values are taken as currency. The currency symbol can be set via SET CURRENCY TO '€ ' for example for Euro, or 'EUR ', whatever your currency is. And that's it.
Bye, Olaf.