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	$66.48	5.507%	$70.1411	$70.14	$70.15	$70.10
Purchase #2	$186.58	6.767%	$199.2059	$199.21	$199.20	$199.20
Purchase #3	$149.69	12.285%	$168.0794	$168.08	$168.10	$168.10
Purchase #4	$216.48	13.284%	$245.2372	$245.24	$245.25	$245.20
Purchase #5	$98.48	13.249%	$111.5276	$111.53	$111.55	$111.50
Purchase #6	$222.82	4.364%	$232.5439	$232.54	$232.55	$232.50
Purchase #7	$27.76	5.861%	$29.387	$29.39	$29.40	$29.40
7 purchase totals =	$968.29		$1,056.1221	$1,056.13	$1,056.20	$1,056.00