Stored Procedure Addressing Generic Table

I want to use ONE stored procedure to update/insert about 300 tables in a database. I hoped this code would work but it gives me an error:

ALTER PROCEDURE [dbo].[InsertRowsTick]
@tableName varchar,
@bid float,
@ask float,
@last float,
@volume int,
@dateTimed DateTime
AS
BEGIN
SET NOCOUNT ON;
INSERT INTO tableName (
bid,
ask,
last,
volume,
dateTimed)
Values (
@bid,
@ask,
@last,
@volume,
@dateTimed)
END

When I (1) commented out @tableName parameter and (2) instead of INSERT INTO tableName wrote: INSERT INTO <realtableName> the code (C#) executed and the table was filled.

How can I use a generic table name as a parameter?

Thanks.