Use a Do...While loop to keep reading records until you've reached the end of the file:
Sub ImportAll()
ThisFile = "C:\sales.txt"
Open ThisFile For Input As #1
Ctr = 0
Do
Line Input #1, Data
Ctr = Ctr + 1
Cells(Ctr, 1).Value = Data
Loop While EOF(1) = False
Close #1 End Sub