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	$137.69	7.267%	$147.6959	$147.70	$147.70	$147.70
Purchase #2	$106.40	5.621%	$112.3807	$112.38	$112.40	$112.40
Purchase #3	$226.54	13.732%	$257.6485	$257.65	$257.65	$257.60
Purchase #4	$99.73	6.680%	$106.392	$106.39	$106.40	$106.40
Purchase #5	$176.43	13.697%	$200.5956	$200.60	$200.60	$200.60
Purchase #6	$180.87	8.652%	$196.5189	$196.52	$196.50	$196.50
Purchase #7	$133.86	7.222%	$143.5274	$143.53	$143.55	$143.50
7 purchase totals =	$1,061.52		$1,164.7590	$1,164.77	$1,164.80	$1,164.70