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	$205.43	8.525%	$222.9429	$222.94	$222.95	$222.90
Purchase #2	$149.40	6.609%	$159.2738	$159.27	$159.25	$159.30
Purchase #3	$250.68	13.701%	$285.0257	$285.03	$285.05	$285.00
Purchase #4	$145.57	5.522%	$153.6084	$153.61	$153.60	$153.60
Purchase #5	$142.33	11.375%	$158.52	$158.52	$158.50	$158.50
Purchase #6	$137.69	11.564%	$153.6125	$153.61	$153.60	$153.60
Purchase #7	$215.96	7.103%	$231.2996	$231.30	$231.30	$231.30
7 purchase totals =	$1,247.06		$1,364.2829	$1,364.28	$1,364.25	$1,364.20