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	$216.98	4.667%	$227.1065	$227.11	$227.10	$227.10
Purchase #2	$223.87	11.584%	$249.8031	$249.80	$249.80	$249.80
Purchase #3	$205.54	5.516%	$216.8776	$216.88	$216.90	$216.90
Purchase #4	$58.28	5.537%	$61.507	$61.51	$61.50	$61.50
Purchase #5	$111.39	6.836%	$119.0046	$119.00	$119.00	$119.00
Purchase #6	$138.60	3.824%	$143.9001	$143.90	$143.90	$143.90
Purchase #7	$85.85	8.489%	$93.1378	$93.14	$93.15	$93.10
7 purchase totals =	$1,040.51		$1,111.3367	$1,111.34	$1,111.35	$1,111.30