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	$248.62	8.499%	$269.7502	$269.75	$269.75	$269.80
Purchase #2	$72.46	8.443%	$78.5778	$78.58	$78.60	$78.60
Purchase #3	$233.45	4.695%	$244.4105	$244.41	$244.40	$244.40
Purchase #4	$213.34	3.518%	$220.8453	$220.85	$220.85	$220.80
Purchase #5	$195.50	10.636%	$216.2934	$216.29	$216.30	$216.30
Purchase #6	$200.53	7.140%	$214.8478	$214.85	$214.85	$214.80
Purchase #7	$181.83	10.225%	$200.4221	$200.42	$200.40	$200.40
7 purchase totals =	$1,345.73		$1,445.1471	$1,445.15	$1,445.15	$1,445.10