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	$46.67	9.121%	$50.9268	$50.93	$50.95	$50.90
Purchase #2	$39.38	5.858%	$41.6869	$41.69	$41.70	$41.70
Purchase #3	$50.47	13.715%	$57.392	$57.39	$57.40	$57.40
Purchase #4	$149.40	10.700%	$165.3858	$165.39	$165.40	$165.40
Purchase #5	$191.64	12.326%	$215.2615	$215.26	$215.25	$215.30
Purchase #6	$243.47	13.222%	$275.6616	$275.66	$275.65	$275.70
Purchase #7	$237.65	13.454%	$269.6234	$269.62	$269.60	$269.60
7 purchase totals =	$958.68		$1,075.9380	$1,075.94	$1,075.95	$1,076.00