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	$13.64	9.523%	$14.9389	$14.94	$14.95	$14.90
Purchase #2	$152.85	6.365%	$162.5789	$162.58	$162.60	$162.60
Purchase #3	$215.74	3.122%	$222.4754	$222.48	$222.50	$222.50
Purchase #4	$218.89	9.716%	$240.1574	$240.16	$240.15	$240.20
Purchase #5	$148.69	4.662%	$155.6219	$155.62	$155.60	$155.60
Purchase #6	$20.79	8.604%	$22.5788	$22.58	$22.60	$22.60
Purchase #7	$194.25	10.110%	$213.8887	$213.89	$213.90	$213.90
7 purchase totals =	$964.85		$1,032.2400	$1,032.25	$1,032.30	$1,032.30