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	$87.97	5.494%	$92.8031	$92.80	$92.80	$92.80
Purchase #2	$8.47	12.775%	$9.552	$9.55	$9.55	$9.60
Purchase #3	$245.88	8.445%	$266.6446	$266.64	$266.65	$266.60
Purchase #4	$74.89	13.709%	$85.1567	$85.16	$85.15	$85.20
Purchase #5	$167.58	9.509%	$183.5152	$183.52	$183.50	$183.50
Purchase #6	$172.82	5.813%	$182.866	$182.87	$182.85	$182.90
Purchase #7	$179.74	9.560%	$196.9231	$196.92	$196.90	$196.90
7 purchase totals =	$937.35		$1,017.4607	$1,017.46	$1,017.40	$1,017.50