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	$147.29	7.546%	$158.4045	$158.40	$158.40	$158.40
Purchase #2	$161.31	7.548%	$173.4857	$173.49	$173.50	$173.50
Purchase #3	$120.89	13.161%	$136.8003	$136.80	$136.80	$136.80
Purchase #4	$177.76	12.804%	$200.5204	$200.52	$200.50	$200.50
Purchase #5	$205.83	9.702%	$225.7996	$225.80	$225.80	$225.80
Purchase #6	$103.57	10.361%	$114.3009	$114.30	$114.30	$114.30
Purchase #7	$156.56	6.666%	$166.9963	$167.00	$167.00	$167.00
7 purchase totals =	$1,073.21		$1,176.3077	$1,176.31	$1,176.30	$1,176.30