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	$136.95	11.486%	$152.6801	$152.68	$152.70	$152.70
Purchase #2	$175.98	11.420%	$196.0769	$196.08	$196.10	$196.10
Purchase #3	$142.85	6.315%	$151.871	$151.87	$151.85	$151.90
Purchase #4	$208.72	4.230%	$217.5489	$217.55	$217.55	$217.50
Purchase #5	$107.99	3.581%	$111.8571	$111.86	$111.85	$111.90
Purchase #6	$95.68	10.796%	$106.0096	$106.01	$106.00	$106.00
Purchase #7	$117.38	9.642%	$128.6978	$128.70	$128.70	$128.70
7 purchase totals =	$985.55		$1,064.7414	$1,064.75	$1,064.75	$1,064.80