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	$213.57	4.522%	$223.2276	$223.23	$223.25	$223.20
Purchase #2	$230.73	5.393%	$243.1733	$243.17	$243.15	$243.20
Purchase #3	$147.34	6.779%	$157.3282	$157.33	$157.35	$157.30
Purchase #4	$79.82	7.522%	$85.8241	$85.82	$85.80	$85.80
Purchase #5	$151.57	4.836%	$158.8999	$158.90	$158.90	$158.90
Purchase #6	$139.73	10.413%	$154.2801	$154.28	$154.30	$154.30
Purchase #7	$119.88	9.225%	$130.9389	$130.94	$130.95	$130.90
7 purchase totals =	$1,082.64		$1,153.6721	$1,153.67	$1,153.70	$1,153.60