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	$89.40	7.322%	$95.9459	$95.95	$95.95	$95.90
Purchase #2	$207.59	4.280%	$216.4749	$216.47	$216.45	$216.50
Purchase #3	$38.83	12.697%	$43.7602	$43.76	$43.75	$43.80
Purchase #4	$53.57	11.820%	$59.902	$59.90	$59.90	$59.90
Purchase #5	$185.55	12.176%	$208.1426	$208.14	$208.15	$208.10
Purchase #6	$239.66	11.358%	$266.8806	$266.88	$266.90	$266.90
Purchase #7	$101.85	8.599%	$110.6081	$110.61	$110.60	$110.60
7 purchase totals =	$916.45		$1,001.7143	$1,001.71	$1,001.70	$1,001.70