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	$59.84	8.692%	$65.0413	$65.04	$65.05	$65.00
Purchase #2	$68.80	13.457%	$78.0584	$78.06	$78.05	$78.10
Purchase #3	$110.45	3.725%	$114.5643	$114.56	$114.55	$114.60
Purchase #4	$104.82	12.433%	$117.8523	$117.85	$117.85	$117.90
Purchase #5	$172.70	12.613%	$194.4827	$194.48	$194.50	$194.50
Purchase #6	$192.41	8.421%	$208.6128	$208.61	$208.60	$208.60
Purchase #7	$242.33	11.194%	$269.4564	$269.46	$269.45	$269.50
7 purchase totals =	$951.35		$1,048.0682	$1,048.06	$1,048.05	$1,048.20