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	$175.86	13.468%	$199.5448	$199.54	$199.55	$199.50
Purchase #2	$127.83	5.322%	$134.6331	$134.63	$134.65	$134.60
Purchase #3	$151.46	4.707%	$158.5892	$158.59	$158.60	$158.60
Purchase #4	$173.25	7.810%	$186.7808	$186.78	$186.80	$186.80
Purchase #5	$105.98	7.308%	$113.725	$113.73	$113.75	$113.70
Purchase #6	$212.57	13.204%	$240.6377	$240.64	$240.65	$240.60
Purchase #7	$16.60	11.522%	$18.5127	$18.51	$18.50	$18.50
7 purchase totals =	$963.55		$1,052.4233	$1,052.42	$1,052.50	$1,052.30