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	$161.47	7.642%	$173.8095	$173.81	$173.80	$173.80
Purchase #2	$200.63	8.423%	$217.5291	$217.53	$217.55	$217.50
Purchase #3	$136.59	13.159%	$154.5639	$154.56	$154.55	$154.60
Purchase #4	$40.34	13.458%	$45.769	$45.77	$45.75	$45.80
Purchase #5	$185.95	6.763%	$198.5258	$198.53	$198.55	$198.50
Purchase #6	$158.90	5.871%	$168.229	$168.23	$168.25	$168.20
Purchase #7	$250.34	6.847%	$267.4808	$267.48	$267.50	$267.50
7 purchase totals =	$1,134.22		$1,225.9071	$1,225.91	$1,225.95	$1,225.90