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	$41.40	10.463%	$45.7317	$45.73	$45.75	$45.70
Purchase #2	$203.43	6.430%	$216.5105	$216.51	$216.50	$216.50
Purchase #3	$244.79	13.639%	$278.1769	$278.18	$278.20	$278.20
Purchase #4	$236.49	5.598%	$249.7287	$249.73	$249.75	$249.70
Purchase #5	$150.81	7.772%	$162.531	$162.53	$162.55	$162.50
Purchase #6	$77.82	6.142%	$82.5997	$82.60	$82.60	$82.60
Purchase #7	$74.69	5.243%	$78.606	$78.61	$78.60	$78.60
7 purchase totals =	$1,029.43		$1,113.8845	$1,113.89	$1,113.95	$1,113.80