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	$149.98	7.395%	$161.071	$161.07	$161.05	$161.10
Purchase #2	$5.82	10.222%	$6.4149	$6.41	$6.40	$6.40
Purchase #3	$210.26	5.510%	$221.8453	$221.85	$221.85	$221.80
Purchase #4	$131.62	12.586%	$148.1857	$148.19	$148.20	$148.20
Purchase #5	$137.67	10.575%	$152.2286	$152.23	$152.25	$152.20
Purchase #6	$183.78	4.436%	$191.9325	$191.93	$191.95	$191.90
Purchase #7	$230.69	4.839%	$241.8531	$241.85	$241.85	$241.90
7 purchase totals =	$1,049.82		$1,123.5311	$1,123.53	$1,123.55	$1,123.50