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	$161.63	13.849%	$184.0141	$184.01	$184.00	$184.00
Purchase #2	$183.49	3.419%	$189.7635	$189.76	$189.75	$189.80
Purchase #3	$193.77	11.287%	$215.6408	$215.64	$215.65	$215.60
Purchase #4	$18.30	11.479%	$20.4007	$20.40	$20.40	$20.40
Purchase #5	$144.97	6.728%	$154.7236	$154.72	$154.70	$154.70
Purchase #6	$208.59	5.653%	$220.3816	$220.38	$220.40	$220.40
Purchase #7	$72.47	7.849%	$78.1582	$78.16	$78.15	$78.20
7 purchase totals =	$983.22		$1,063.0825	$1,063.07	$1,063.05	$1,063.10