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	$162.45	7.473%	$174.5899	$174.59	$174.60	$174.60
Purchase #2	$169.50	12.831%	$191.2485	$191.25	$191.25	$191.20
Purchase #3	$149.58	4.547%	$156.3814	$156.38	$156.40	$156.40
Purchase #4	$37.57	3.347%	$38.8275	$38.83	$38.85	$38.80
Purchase #5	$144.31	4.611%	$150.9641	$150.96	$150.95	$151.00
Purchase #6	$90.83	11.140%	$100.9485	$100.95	$100.95	$100.90
Purchase #7	$193.66	5.271%	$203.8678	$203.87	$203.85	$203.90
7 purchase totals =	$947.90		$1,016.8277	$1,016.83	$1,016.85	$1,016.80