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	$111.86	4.750%	$117.1734	$117.17	$117.15	$117.20
Purchase #2	$102.64	3.250%	$105.9758	$105.98	$106.00	$106.00
Purchase #3	$85.72	7.584%	$92.221	$92.22	$92.20	$92.20
Purchase #4	$208.94	7.179%	$223.9398	$223.94	$223.95	$223.90
Purchase #5	$156.41	8.669%	$169.9692	$169.97	$169.95	$170.00
Purchase #6	$87.81	13.205%	$99.4053	$99.41	$99.40	$99.40
Purchase #7	$202.45	10.594%	$223.8976	$223.90	$223.90	$223.90
7 purchase totals =	$955.83		$1,032.5821	$1,032.59	$1,032.55	$1,032.60