If your input is coma separated then you can split the input and process it like below
string totals = txttotal.Text.Split(',');
foreach(string total in totals)
since you havent told how you want to process the txttotal input am just putting the number split code alone. You may adjust this to your requirement.
Use the Decimal.TryParse or Parse as suggested by SA in Solution 1
] for conversions.