Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$181.30	9.508%	$198.538	$198.54	$198.55	$198.50
Purchase #2	$44.66	6.180%	$47.42	$47.42	$47.40	$47.40
Purchase #3	$54.97	10.697%	$60.8501	$60.85	$60.85	$60.90
Purchase #4	$103.67	3.731%	$107.5379	$107.54	$107.55	$107.50
Purchase #5	$196.87	4.543%	$205.8138	$205.81	$205.80	$205.80
Purchase #6	$78.75	8.123%	$85.1469	$85.15	$85.15	$85.10
Purchase #7	$81.86	11.181%	$91.0128	$91.01	$91.00	$91.00
7 purchase totals =	$742.08		$796.3195	$796.32	$796.30	$796.20