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	$59.48	13.539%	$67.533	$67.53	$67.55	$67.50
Purchase #2	$105.70	9.434%	$115.6717	$115.67	$115.65	$115.70
Purchase #3	$183.76	7.162%	$196.9209	$196.92	$196.90	$196.90
Purchase #4	$235.98	7.521%	$253.7281	$253.73	$253.75	$253.70
Purchase #5	$207.69	6.441%	$221.0673	$221.07	$221.05	$221.10
Purchase #6	$150.47	3.378%	$155.5529	$155.55	$155.55	$155.60
Purchase #7	$49.36	9.194%	$53.8982	$53.90	$53.90	$53.90
7 purchase totals =	$992.44		$1,064.3721	$1,064.37	$1,064.35	$1,064.40