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	$227.39	11.392%	$253.2943	$253.29	$253.30	$253.30
Purchase #2	$172.36	7.769%	$185.7506	$185.75	$185.75	$185.80
Purchase #3	$194.39	11.162%	$216.0878	$216.09	$216.10	$216.10
Purchase #4	$226.43	6.240%	$240.5592	$240.56	$240.55	$240.60
Purchase #5	$177.78	4.460%	$185.709	$185.71	$185.70	$185.70
Purchase #6	$173.52	10.563%	$191.8489	$191.85	$191.85	$191.80
Purchase #7	$192.54	4.268%	$200.7576	$200.76	$200.75	$200.80
7 purchase totals =	$1,364.41		$1,474.0074	$1,474.01	$1,474.00	$1,474.10