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	$196.39	5.192%	$206.5866	$206.59	$206.60	$206.60
Purchase #2	$128.34	7.283%	$137.687	$137.69	$137.70	$137.70
Purchase #3	$141.89	6.530%	$151.1554	$151.16	$151.15	$151.20
Purchase #4	$173.72	5.638%	$183.5143	$183.51	$183.50	$183.50
Purchase #5	$24.34	12.557%	$27.3964	$27.40	$27.40	$27.40
Purchase #6	$166.80	7.176%	$178.7696	$178.77	$178.75	$178.80
Purchase #7	$148.84	13.286%	$168.6149	$168.61	$168.60	$168.60
7 purchase totals =	$980.32		$1,053.7242	$1,053.73	$1,053.70	$1,053.80