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	$86.49	10.833%	$95.8595	$95.86	$95.85	$95.90
Purchase #2	$229.85	8.388%	$249.1298	$249.13	$249.15	$249.10
Purchase #3	$52.73	12.787%	$59.4726	$59.47	$59.45	$59.50
Purchase #4	$122.95	3.649%	$127.4364	$127.44	$127.45	$127.40
Purchase #5	$223.46	10.825%	$247.6495	$247.65	$247.65	$247.60
Purchase #6	$130.66	10.293%	$144.1088	$144.11	$144.10	$144.10
Purchase #7	$236.34	7.167%	$253.2785	$253.28	$253.30	$253.30
7 purchase totals =	$1,082.48		$1,176.9351	$1,176.94	$1,176.95	$1,176.90