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	$94.32	9.625%	$103.3983	$103.40	$103.40	$103.40
Purchase #2	$76.85	3.169%	$79.2854	$79.29	$79.30	$79.30
Purchase #3	$131.89	12.576%	$148.4765	$148.48	$148.50	$148.50
Purchase #4	$99.34	8.180%	$107.466	$107.47	$107.45	$107.50
Purchase #5	$176.25	11.618%	$196.7267	$196.73	$196.75	$196.70
Purchase #6	$205.64	5.280%	$216.4978	$216.50	$216.50	$216.50
Purchase #7	$232.90	8.832%	$253.4697	$253.47	$253.45	$253.50
7 purchase totals =	$1,017.19		$1,105.3204	$1,105.34	$1,105.35	$1,105.40