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	$193.62	3.721%	$200.8246	$200.82	$200.80	$200.80
Purchase #2	$98.91	10.721%	$109.5141	$109.51	$109.50	$109.50
Purchase #3	$105.68	6.525%	$112.5756	$112.58	$112.60	$112.60
Purchase #4	$51.86	4.343%	$54.1123	$54.11	$54.10	$54.10
Purchase #5	$149.74	4.766%	$156.8766	$156.88	$156.90	$156.90
Purchase #6	$163.39	11.729%	$182.554	$182.55	$182.55	$182.60
Purchase #7	$98.95	13.224%	$112.0351	$112.04	$112.05	$112.00
7 purchase totals =	$862.15		$928.4923	$928.49	$928.50	$928.50