Textbox Display

I have 3 textboxes, 2 to input and 1 to display. box1 input a value onto the sheet as say txtInvVal.Text = Cells(Currentrow,1).Value.
box2 as txtVat.Text = Cells(Currentrow,100).Value

The output is then calculated as
Cells(Currentrow,1).Value * Cells(Currentrow,100).Value = txtPayVat

Even though the inputs to the boxes are 2 decimel places, say, box1 39.5
box2 0.175 the resultant display can be 5 or 6 decimal places long.

Is there anyway to correct this please.