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	$103.46	7.283%	$110.995	$111.00	$111.00	$111.00
Purchase #2	$154.38	3.196%	$159.314	$159.31	$159.30	$159.30
Purchase #3	$182.61	7.426%	$196.1706	$196.17	$196.15	$196.20
Purchase #4	$133.55	4.457%	$139.5023	$139.50	$139.50	$139.50
Purchase #5	$204.51	6.776%	$218.3676	$218.37	$218.35	$218.40
Purchase #6	$74.34	11.383%	$82.8021	$82.80	$82.80	$82.80
Purchase #7	$126.39	10.637%	$139.8341	$139.83	$139.85	$139.80
7 purchase totals =	$979.24		$1,046.9857	$1,046.98	$1,046.95	$1,047.00