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	$71.85	7.353%	$77.1331	$77.13	$77.15	$77.10
Purchase #2	$10.61	6.161%	$11.2637	$11.26	$11.25	$11.30
Purchase #3	$20.86	4.759%	$21.8527	$21.85	$21.85	$21.90
Purchase #4	$163.33	10.415%	$180.3408	$180.34	$180.35	$180.30
Purchase #5	$58.45	7.636%	$62.9132	$62.91	$62.90	$62.90
Purchase #6	$40.90	4.774%	$42.8526	$42.85	$42.85	$42.90
Purchase #7	$81.95	5.180%	$86.195	$86.20	$86.20	$86.20
7 purchase totals =	$447.95		$482.5511	$482.54	$482.55	$482.60