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	$205.39	8.489%	$222.8256	$222.83	$222.85	$222.80
Purchase #2	$104.55	6.656%	$111.5088	$111.51	$111.50	$111.50
Purchase #3	$180.33	10.463%	$199.1979	$199.20	$199.20	$199.20
Purchase #4	$54.75	10.757%	$60.6395	$60.64	$60.65	$60.60
Purchase #5	$142.83	7.774%	$153.9336	$153.93	$153.95	$153.90
Purchase #6	$240.59	9.266%	$262.8831	$262.88	$262.90	$262.90
Purchase #7	$59.74	7.527%	$64.2366	$64.24	$64.25	$64.20
7 purchase totals =	$988.18		$1,075.2251	$1,075.23	$1,075.30	$1,075.10