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	$196.25	13.232%	$222.2178	$222.22	$222.20	$222.20
Purchase #2	$219.54	5.519%	$231.6564	$231.66	$231.65	$231.70
Purchase #3	$115.64	10.444%	$127.7174	$127.72	$127.70	$127.70
Purchase #4	$166.74	7.120%	$178.6119	$178.61	$178.60	$178.60
Purchase #5	$158.43	7.371%	$170.1079	$170.11	$170.10	$170.10
Purchase #6	$29.29	10.451%	$32.3511	$32.35	$32.35	$32.40
Purchase #7	$84.63	4.446%	$88.3926	$88.39	$88.40	$88.40
7 purchase totals =	$970.52		$1,051.0551	$1,051.06	$1,051.00	$1,051.10