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	$196.49	13.520%	$223.0554	$223.06	$223.05	$223.10
Purchase #2	$213.98	7.359%	$229.7268	$229.73	$229.75	$229.70
Purchase #3	$49.43	6.475%	$52.6306	$52.63	$52.65	$52.60
Purchase #4	$219.80	4.257%	$229.1569	$229.16	$229.15	$229.20
Purchase #5	$133.55	13.420%	$151.4724	$151.47	$151.45	$151.50
Purchase #6	$169.86	7.488%	$182.5791	$182.58	$182.60	$182.60
Purchase #7	$39.27	6.791%	$41.9368	$41.94	$41.95	$41.90
7 purchase totals =	$1,022.38		$1,110.5580	$1,110.57	$1,110.60	$1,110.60