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	$189.53	4.164%	$197.422	$197.42	$197.40	$197.40
Purchase #2	$158.31	5.118%	$166.4123	$166.41	$166.40	$166.40
Purchase #3	$84.89	5.625%	$89.6651	$89.67	$89.65	$89.70
Purchase #4	$110.59	9.336%	$120.9147	$120.91	$120.90	$120.90
Purchase #5	$187.83	4.761%	$196.7726	$196.77	$196.75	$196.80
Purchase #6	$148.83	6.797%	$158.946	$158.95	$158.95	$158.90
Purchase #7	$215.72	3.762%	$223.8354	$223.84	$223.85	$223.80
7 purchase totals =	$1,095.70		$1,153.9681	$1,153.97	$1,153.90	$1,153.90