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	$67.55	3.244%	$69.7413	$69.74	$69.75	$69.70
Purchase #2	$151.25	3.460%	$156.4833	$156.48	$156.50	$156.50
Purchase #3	$58.67	4.538%	$61.3324	$61.33	$61.35	$61.30
Purchase #4	$236.72	8.104%	$255.9038	$255.90	$255.90	$255.90
Purchase #5	$221.82	13.419%	$251.586	$251.59	$251.60	$251.60
Purchase #6	$55.25	7.269%	$59.2661	$59.27	$59.25	$59.30
Purchase #7	$193.82	5.583%	$204.641	$204.64	$204.65	$204.60
7 purchase totals =	$985.08		$1,058.9539	$1,058.95	$1,059.00	$1,058.90