You would not just add them together. You should receive a W-2 because the company would withhold tax on the pay per delivery and the tips would be in a separate box on the W-2 in Box 12 with a code of A. This entry indicates the employer did not withhold social security or medicare on your tips and that tax would have to be paid when you file your return.
If you receive a 1099-MISC from the pizza company, you could add them together because you pay social security and medicare on ALL the net profit from your self-employment income.
Don't file until you know if your employer is sending you a W-2 or a 1099-MISC
