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	$74.36	4.827%	$77.9494	$77.95	$77.95	$77.90
Purchase #2	$158.76	5.524%	$167.5299	$167.53	$167.55	$167.50
Purchase #3	$237.99	7.521%	$255.8892	$255.89	$255.90	$255.90
Purchase #4	$148.38	13.151%	$167.8935	$167.89	$167.90	$167.90
Purchase #5	$161.51	10.116%	$177.8484	$177.85	$177.85	$177.80
Purchase #6	$149.58	12.372%	$168.086	$168.09	$168.10	$168.10
Purchase #7	$111.31	6.170%	$118.1778	$118.18	$118.20	$118.20
7 purchase totals =	$1,041.89		$1,133.3742	$1,133.38	$1,133.45	$1,133.30