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	$203.27	6.391%	$216.261	$216.26	$216.25	$216.30
Purchase #2	$108.89	5.687%	$115.0826	$115.08	$115.10	$115.10
Purchase #3	$80.85	10.465%	$89.311	$89.31	$89.30	$89.30
Purchase #4	$12.51	6.845%	$13.3663	$13.37	$13.35	$13.40
Purchase #5	$115.74	6.480%	$123.24	$123.24	$123.25	$123.20
Purchase #6	$239.73	13.521%	$272.1439	$272.14	$272.15	$272.10
Purchase #7	$243.81	13.244%	$276.1002	$276.10	$276.10	$276.10
7 purchase totals =	$1,004.80		$1,105.5050	$1,105.50	$1,105.50	$1,105.50