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	$241.62	8.327%	$261.7397	$261.74	$261.75	$261.70
Purchase #2	$229.98	9.214%	$251.1704	$251.17	$251.15	$251.20
Purchase #3	$37.75	12.532%	$42.4808	$42.48	$42.50	$42.50
Purchase #4	$69.47	7.111%	$74.41	$74.41	$74.40	$74.40
Purchase #5	$249.80	5.130%	$262.6147	$262.61	$262.60	$262.60
Purchase #6	$182.94	4.704%	$191.5455	$191.55	$191.55	$191.50
Purchase #7	$92.90	8.572%	$100.8634	$100.86	$100.85	$100.90
7 purchase totals =	$1,104.46		$1,184.8245	$1,184.82	$1,184.80	$1,184.80