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	$176.46	3.221%	$182.1438	$182.14	$182.15	$182.10
Purchase #2	$206.31	5.507%	$217.6715	$217.67	$217.65	$217.70
Purchase #3	$32.43	3.137%	$33.4473	$33.45	$33.45	$33.40
Purchase #4	$212.37	6.634%	$226.4586	$226.46	$226.45	$226.50
Purchase #5	$183.37	3.690%	$190.1364	$190.14	$190.15	$190.10
Purchase #6	$171.45	13.388%	$194.4037	$194.40	$194.40	$194.40
Purchase #7	$105.43	6.621%	$112.4105	$112.41	$112.40	$112.40
7 purchase totals =	$1,087.82		$1,156.6718	$1,156.67	$1,156.65	$1,156.60