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	$187.34	7.448%	$201.2931	$201.29	$201.30	$201.30
Purchase #2	$70.83	10.792%	$78.474	$78.47	$78.45	$78.50
Purchase #3	$246.99	11.475%	$275.3321	$275.33	$275.35	$275.30
Purchase #4	$111.93	10.162%	$123.3043	$123.30	$123.30	$123.30
Purchase #5	$46.29	13.112%	$52.3595	$52.36	$52.35	$52.40
Purchase #6	$208.51	8.546%	$226.3293	$226.33	$226.35	$226.30
Purchase #7	$116.45	10.136%	$128.2534	$128.25	$128.25	$128.30
7 purchase totals =	$988.34		$1,085.3457	$1,085.33	$1,085.35	$1,085.40