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	$62.38	8.844%	$67.8969	$67.90	$67.90	$67.90
Purchase #2	$75.79	4.864%	$79.4764	$79.48	$79.50	$79.50
Purchase #3	$10.51	6.385%	$11.1811	$11.18	$11.20	$11.20
Purchase #4	$111.36	5.867%	$117.8935	$117.89	$117.90	$117.90
Purchase #5	$239.26	9.550%	$262.1093	$262.11	$262.10	$262.10
Purchase #6	$133.32	4.574%	$139.4181	$139.42	$139.40	$139.40
Purchase #7	$83.36	9.749%	$91.4868	$91.49	$91.50	$91.50
7 purchase totals =	$715.98		$769.4621	$769.47	$769.50	$769.50