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	$72.29	5.258%	$76.091	$76.09	$76.10	$76.10
Purchase #2	$130.33	7.613%	$140.252	$140.25	$140.25	$140.30
Purchase #3	$95.43	5.691%	$100.8609	$100.86	$100.85	$100.90
Purchase #4	$67.76	9.626%	$74.2826	$74.28	$74.30	$74.30
Purchase #5	$39.80	6.372%	$42.3361	$42.34	$42.35	$42.30
Purchase #6	$164.78	7.255%	$176.7348	$176.73	$176.75	$176.70
Purchase #7	$40.59	10.613%	$44.8978	$44.90	$44.90	$44.90
7 purchase totals =	$610.98		$655.4552	$655.45	$655.50	$655.50