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	$209.66	4.801%	$219.7258	$219.73	$219.75	$219.70
Purchase #2	$156.73	7.112%	$167.8766	$167.88	$167.90	$167.90
Purchase #3	$95.40	4.521%	$99.713	$99.71	$99.70	$99.70
Purchase #4	$67.50	13.605%	$76.6834	$76.68	$76.70	$76.70
Purchase #5	$9.96	13.247%	$11.2794	$11.28	$11.30	$11.30
Purchase #6	$183.86	11.624%	$205.2319	$205.23	$205.25	$205.20
Purchase #7	$241.52	10.759%	$267.5051	$267.51	$267.50	$267.50
7 purchase totals =	$964.63		$1,048.0152	$1,048.02	$1,048.10	$1,048.00