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	$184.55	6.537%	$196.614	$196.61	$196.60	$196.60
Purchase #2	$88.43	11.536%	$98.6313	$98.63	$98.65	$98.60
Purchase #3	$74.90	4.806%	$78.4997	$78.50	$78.50	$78.50
Purchase #4	$151.88	13.365%	$172.1788	$172.18	$172.20	$172.20
Purchase #5	$175.91	4.194%	$183.2877	$183.29	$183.30	$183.30
Purchase #6	$199.63	7.462%	$214.5264	$214.53	$214.55	$214.50
Purchase #7	$71.39	10.657%	$78.998	$79.00	$79.00	$79.00
7 purchase totals =	$946.69		$1,022.7359	$1,022.74	$1,022.80	$1,022.70