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	$158.54	9.395%	$173.4348	$173.43	$173.45	$173.40
Purchase #2	$182.62	5.232%	$192.1747	$192.17	$192.15	$192.20
Purchase #3	$94.59	6.179%	$100.4347	$100.43	$100.45	$100.40
Purchase #4	$126.83	4.677%	$132.7618	$132.76	$132.75	$132.80
Purchase #5	$92.39	4.810%	$96.834	$96.83	$96.85	$96.80
Purchase #6	$215.57	11.689%	$240.768	$240.77	$240.75	$240.80
Purchase #7	$163.63	3.125%	$168.7434	$168.74	$168.75	$168.70
7 purchase totals =	$1,034.17		$1,105.1514	$1,105.13	$1,105.15	$1,105.10