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	$168.65	4.295%	$175.8935	$175.89	$175.90	$175.90
Purchase #2	$106.78	4.131%	$111.1911	$111.19	$111.20	$111.20
Purchase #3	$180.53	8.344%	$195.5934	$195.59	$195.60	$195.60
Purchase #4	$147.54	9.453%	$161.487	$161.49	$161.50	$161.50
Purchase #5	$67.99	5.697%	$71.8634	$71.86	$71.85	$71.90
Purchase #6	$175.70	3.155%	$181.2433	$181.24	$181.25	$181.20
Purchase #7	$144.32	6.846%	$154.2001	$154.20	$154.20	$154.20
7 purchase totals =	$991.51		$1,051.4718	$1,051.46	$1,051.50	$1,051.50