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	$190.27	5.452%	$200.6435	$200.64	$200.65	$200.60
Purchase #2	$33.29	3.185%	$34.3503	$34.35	$34.35	$34.40
Purchase #3	$184.61	8.298%	$199.9289	$199.93	$199.95	$199.90
Purchase #4	$139.54	13.188%	$157.9425	$157.94	$157.95	$157.90
Purchase #5	$107.36	6.318%	$114.143	$114.14	$114.15	$114.10
Purchase #6	$43.51	4.558%	$45.4932	$45.49	$45.50	$45.50
Purchase #7	$238.98	8.194%	$258.562	$258.56	$258.55	$258.60
7 purchase totals =	$937.56		$1,011.0634	$1,011.05	$1,011.10	$1,011.00