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	$223.71	5.817%	$236.7232	$236.72	$236.70	$236.70
Purchase #2	$176.34	5.254%	$185.6049	$185.60	$185.60	$185.60
Purchase #3	$57.30	6.674%	$61.1242	$61.12	$61.10	$61.10
Purchase #4	$122.92	7.671%	$132.3492	$132.35	$132.35	$132.30
Purchase #5	$241.40	6.423%	$256.9051	$256.91	$256.90	$256.90
Purchase #6	$119.75	7.113%	$128.2678	$128.27	$128.25	$128.30
Purchase #7	$231.44	5.863%	$245.0093	$245.01	$245.00	$245.00
7 purchase totals =	$1,172.86		$1,245.9837	$1,245.98	$1,245.90	$1,245.90