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	$97.64	11.163%	$108.5396	$108.54	$108.55	$108.50
Purchase #2	$104.69	5.795%	$110.7568	$110.76	$110.75	$110.80
Purchase #3	$248.54	6.576%	$264.884	$264.88	$264.90	$264.90
Purchase #4	$247.30	12.273%	$277.6511	$277.65	$277.65	$277.70
Purchase #5	$133.73	6.688%	$142.6739	$142.67	$142.65	$142.70
Purchase #6	$145.75	13.136%	$164.8957	$164.90	$164.90	$164.90
Purchase #7	$114.61	10.693%	$126.8652	$126.87	$126.85	$126.90
7 purchase totals =	$1,092.26		$1,196.2663	$1,196.27	$1,196.25	$1,196.40