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	$205.27	11.423%	$228.718	$228.72	$228.70	$228.70
Purchase #2	$208.48	12.171%	$233.8541	$233.85	$233.85	$233.90
Purchase #3	$38.56	6.621%	$41.1131	$41.11	$41.10	$41.10
Purchase #4	$203.41	12.386%	$228.6044	$228.60	$228.60	$228.60
Purchase #5	$50.25	12.540%	$56.5514	$56.55	$56.55	$56.60
Purchase #6	$52.62	10.144%	$57.9578	$57.96	$57.95	$58.00
Purchase #7	$246.83	3.271%	$254.9038	$254.90	$254.90	$254.90
7 purchase totals =	$1,005.42		$1,101.7026	$1,101.69	$1,101.65	$1,101.80