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	$212.65	4.659%	$222.5574	$222.56	$222.55	$222.60
Purchase #2	$61.49	7.158%	$65.8915	$65.89	$65.90	$65.90
Purchase #3	$61.75	6.486%	$65.7551	$65.76	$65.75	$65.80
Purchase #4	$250.49	5.593%	$264.4999	$264.50	$264.50	$264.50
Purchase #5	$226.78	7.698%	$244.2375	$244.24	$244.25	$244.20
Purchase #6	$151.75	9.244%	$165.7778	$165.78	$165.80	$165.80
Purchase #7	$198.29	10.241%	$218.5969	$218.60	$218.60	$218.60
7 purchase totals =	$1,163.20		$1,247.3161	$1,247.33	$1,247.35	$1,247.40