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	$104.80	6.576%	$111.6916	$111.69	$111.70	$111.70
Purchase #2	$29.42	6.637%	$31.3726	$31.37	$31.35	$31.40
Purchase #3	$230.59	10.741%	$255.3577	$255.36	$255.35	$255.40
Purchase #4	$144.32	11.469%	$160.8721	$160.87	$160.85	$160.90
Purchase #5	$237.78	3.193%	$245.3723	$245.37	$245.35	$245.40
Purchase #6	$158.44	4.651%	$165.809	$165.81	$165.80	$165.80
Purchase #7	$81.34	11.781%	$90.9227	$90.92	$90.90	$90.90
7 purchase totals =	$986.69		$1,061.3980	$1,061.39	$1,061.30	$1,061.50