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	$190.35	11.674%	$212.5715	$212.57	$212.55	$212.60
Purchase #2	$80.74	6.462%	$85.9574	$85.96	$85.95	$86.00
Purchase #3	$148.76	6.451%	$158.3565	$158.36	$158.35	$158.40
Purchase #4	$84.43	6.111%	$89.5895	$89.59	$89.60	$89.60
Purchase #5	$210.82	9.655%	$231.1747	$231.17	$231.15	$231.20
Purchase #6	$69.82	13.279%	$79.0914	$79.09	$79.10	$79.10
Purchase #7	$246.29	9.333%	$269.2762	$269.28	$269.30	$269.30
7 purchase totals =	$1,031.21		$1,126.0172	$1,126.02	$1,126.00	$1,126.20