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	$59.82	3.753%	$62.065	$62.07	$62.05	$62.10
Purchase #2	$6.95	6.462%	$7.3991	$7.40	$7.40	$7.40
Purchase #3	$134.65	7.298%	$144.4768	$144.48	$144.50	$144.50
Purchase #4	$230.75	13.241%	$261.3036	$261.30	$261.30	$261.30
Purchase #5	$164.75	13.567%	$187.1016	$187.10	$187.10	$187.10
Purchase #6	$219.83	6.639%	$234.4245	$234.42	$234.40	$234.40
Purchase #7	$61.88	9.458%	$67.7326	$67.73	$67.75	$67.70
7 purchase totals =	$878.63		$964.5032	$964.50	$964.50	$964.50