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	$247.95	6.323%	$263.6279	$263.63	$263.65	$263.60
Purchase #2	$17.37	5.732%	$18.3656	$18.37	$18.35	$18.40
Purchase #3	$61.35	12.640%	$69.1046	$69.10	$69.10	$69.10
Purchase #4	$216.44	3.628%	$224.2924	$224.29	$224.30	$224.30
Purchase #5	$196.51	12.692%	$221.451	$221.45	$221.45	$221.50
Purchase #6	$130.70	7.228%	$140.147	$140.15	$140.15	$140.10
Purchase #7	$100.76	4.724%	$105.5199	$105.52	$105.50	$105.50
7 purchase totals =	$971.08		$1,042.5084	$1,042.51	$1,042.50	$1,042.50