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	$87.95	4.488%	$91.8972	$91.90	$91.90	$91.90
Purchase #2	$190.99	4.483%	$199.5521	$199.55	$199.55	$199.60
Purchase #3	$139.83	4.286%	$145.8231	$145.82	$145.80	$145.80
Purchase #4	$98.25	7.666%	$105.7818	$105.78	$105.80	$105.80
Purchase #5	$203.66	4.307%	$212.4316	$212.43	$212.45	$212.40
Purchase #6	$227.25	10.278%	$250.6068	$250.61	$250.60	$250.60
Purchase #7	$9.72	9.385%	$10.6322	$10.63	$10.65	$10.60
7 purchase totals =	$957.65		$1,016.7248	$1,016.72	$1,016.75	$1,016.70