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	$190.49	11.491%	$212.3792	$212.38	$212.40	$212.40
Purchase #2	$137.37	10.418%	$151.6812	$151.68	$151.70	$151.70
Purchase #3	$182.50	11.565%	$203.6061	$203.61	$203.60	$203.60
Purchase #4	$195.73	11.289%	$217.826	$217.83	$217.85	$217.80
Purchase #5	$196.38	13.586%	$223.0602	$223.06	$223.05	$223.10
Purchase #6	$78.56	12.641%	$88.4908	$88.49	$88.50	$88.50
Purchase #7	$102.71	8.653%	$111.5975	$111.60	$111.60	$111.60
7 purchase totals =	$1,083.74		$1,208.6410	$1,208.65	$1,208.70	$1,208.70