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	$209.65	11.200%	$233.1308	$233.13	$233.15	$233.10
Purchase #2	$48.85	13.146%	$55.2718	$55.27	$55.25	$55.30
Purchase #3	$86.69	11.341%	$96.5215	$96.52	$96.50	$96.50
Purchase #4	$25.27	4.646%	$26.444	$26.44	$26.45	$26.40
Purchase #5	$69.29	13.195%	$78.4328	$78.43	$78.45	$78.40
Purchase #6	$104.67	5.843%	$110.7859	$110.79	$110.80	$110.80
Purchase #7	$123.33	6.133%	$130.8938	$130.89	$130.90	$130.90
7 purchase totals =	$667.75		$731.4806	$731.47	$731.50	$731.40