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	$87.36	9.510%	$95.6679	$95.67	$95.65	$95.70
Purchase #2	$158.56	5.679%	$167.5646	$167.56	$167.55	$167.60
Purchase #3	$160.51	3.850%	$166.6896	$166.69	$166.70	$166.70
Purchase #4	$248.86	12.238%	$279.3155	$279.32	$279.30	$279.30
Purchase #5	$164.33	12.485%	$184.8466	$184.85	$184.85	$184.80
Purchase #6	$13.67	4.532%	$14.2895	$14.29	$14.30	$14.30
Purchase #7	$188.88	8.789%	$205.4807	$205.48	$205.50	$205.50
7 purchase totals =	$1,022.17		$1,113.8544	$1,113.86	$1,113.85	$1,113.90