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	$231.77	13.132%	$262.206	$262.21	$262.20	$262.20
Purchase #2	$86.40	6.455%	$91.9771	$91.98	$92.00	$92.00
Purchase #3	$161.27	5.323%	$169.8544	$169.85	$169.85	$169.90
Purchase #4	$208.55	13.294%	$236.2746	$236.27	$236.25	$236.30
Purchase #5	$117.39	5.309%	$123.6222	$123.62	$123.60	$123.60
Purchase #6	$83.60	6.845%	$89.3224	$89.32	$89.30	$89.30
Purchase #7	$230.37	10.181%	$253.824	$253.82	$253.80	$253.80
7 purchase totals =	$1,119.35		$1,227.0807	$1,227.07	$1,227.00	$1,227.10