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	$217.78	4.491%	$227.5605	$227.56	$227.55	$227.60
Purchase #2	$86.27	6.170%	$91.5929	$91.59	$91.60	$91.60
Purchase #3	$186.28	4.749%	$195.1264	$195.13	$195.15	$195.10
Purchase #4	$229.84	4.525%	$240.2403	$240.24	$240.25	$240.20
Purchase #5	$198.27	6.838%	$211.8277	$211.83	$211.85	$211.80
Purchase #6	$217.31	4.865%	$227.8821	$227.88	$227.90	$227.90
Purchase #7	$19.75	3.728%	$20.4863	$20.49	$20.50	$20.50
7 purchase totals =	$1,155.50		$1,214.7162	$1,214.72	$1,214.80	$1,214.70