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	$165.98	10.116%	$182.7705	$182.77	$182.75	$182.80
Purchase #2	$129.73	5.731%	$137.1648	$137.16	$137.15	$137.20
Purchase #3	$115.28	10.732%	$127.6518	$127.65	$127.65	$127.70
Purchase #4	$95.83	12.627%	$107.9305	$107.93	$107.95	$107.90
Purchase #5	$144.93	9.455%	$158.6331	$158.63	$158.65	$158.60
Purchase #6	$239.25	10.600%	$264.6105	$264.61	$264.60	$264.60
Purchase #7	$171.89	10.679%	$190.2461	$190.25	$190.25	$190.20
7 purchase totals =	$1,062.89		$1,169.0073	$1,169.00	$1,169.00	$1,169.00