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	$56.25	5.159%	$59.1519	$59.15	$59.15	$59.20
Purchase #2	$175.64	8.269%	$190.1637	$190.16	$190.15	$190.20
Purchase #3	$95.31	11.240%	$106.0228	$106.02	$106.00	$106.00
Purchase #4	$247.96	11.429%	$276.2993	$276.30	$276.30	$276.30
Purchase #5	$163.44	10.305%	$180.2825	$180.28	$180.30	$180.30
Purchase #6	$145.67	13.613%	$165.5001	$165.50	$165.50	$165.50
Purchase #7	$53.60	4.213%	$55.8582	$55.86	$55.85	$55.90
7 purchase totals =	$937.87		$1,033.2785	$1,033.27	$1,033.25	$1,033.40