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	$89.61	7.102%	$95.9741	$95.97	$95.95	$96.00
Purchase #2	$131.60	13.849%	$149.8253	$149.83	$149.85	$149.80
Purchase #3	$231.49	10.682%	$256.2178	$256.22	$256.20	$256.20
Purchase #4	$189.58	5.800%	$200.5756	$200.58	$200.60	$200.60
Purchase #5	$9.55	10.852%	$10.5864	$10.59	$10.60	$10.60
Purchase #6	$53.84	7.629%	$57.9475	$57.95	$57.95	$57.90
Purchase #7	$229.83	4.649%	$240.5148	$240.51	$240.50	$240.50
7 purchase totals =	$935.50		$1,011.6415	$1,011.65	$1,011.65	$1,011.60