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	$190.32	10.837%	$210.945	$210.95	$210.95	$210.90
Purchase #2	$19.27	7.815%	$20.776	$20.78	$20.80	$20.80
Purchase #3	$142.84	4.819%	$149.7235	$149.72	$149.70	$149.70
Purchase #4	$96.77	7.298%	$103.8323	$103.83	$103.85	$103.80
Purchase #5	$211.56	7.641%	$227.7253	$227.73	$227.75	$227.70
Purchase #6	$92.85	4.263%	$96.8082	$96.81	$96.80	$96.80
Purchase #7	$108.51	13.709%	$123.3856	$123.39	$123.40	$123.40
7 purchase totals =	$862.12		$933.1959	$933.21	$933.25	$933.10