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	$196.25	9.603%	$215.0959	$215.10	$215.10	$215.10
Purchase #2	$78.73	8.834%	$85.685	$85.69	$85.70	$85.70
Purchase #3	$146.53	9.714%	$160.7639	$160.76	$160.75	$160.80
Purchase #4	$51.52	12.257%	$57.8348	$57.83	$57.85	$57.80
Purchase #5	$187.86	6.869%	$200.7641	$200.76	$200.75	$200.80
Purchase #6	$128.81	9.722%	$141.3329	$141.33	$141.35	$141.30
Purchase #7	$192.99	11.495%	$215.1742	$215.17	$215.15	$215.20
7 purchase totals =	$982.69		$1,076.6508	$1,076.64	$1,076.65	$1,076.70