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	$193.97	7.615%	$208.7408	$208.74	$208.75	$208.70
Purchase #2	$104.77	6.271%	$111.3401	$111.34	$111.35	$111.30
Purchase #3	$139.91	6.285%	$148.7033	$148.70	$148.70	$148.70
Purchase #4	$68.92	9.646%	$75.568	$75.57	$75.55	$75.60
Purchase #5	$69.59	12.697%	$78.4258	$78.43	$78.45	$78.40
Purchase #6	$210.50	5.497%	$222.0712	$222.07	$222.05	$222.10
Purchase #7	$98.36	4.823%	$103.1039	$103.10	$103.10	$103.10
7 purchase totals =	$886.02		$947.9531	$947.95	$947.95	$947.90