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	$184.90	5.346%	$194.7848	$194.78	$194.80	$194.80
Purchase #2	$9.66	7.332%	$10.3683	$10.37	$10.35	$10.40
Purchase #3	$56.79	7.122%	$60.8346	$60.83	$60.85	$60.80
Purchase #4	$169.25	6.284%	$179.8857	$179.89	$179.90	$179.90
Purchase #5	$143.84	7.595%	$154.7646	$154.76	$154.75	$154.80
Purchase #6	$53.51	3.253%	$55.2507	$55.25	$55.25	$55.30
Purchase #7	$51.78	4.112%	$53.9092	$53.91	$53.90	$53.90
7 purchase totals =	$669.73		$709.7979	$709.79	$709.80	$709.90