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	$177.25	8.226%	$191.8306	$191.83	$191.85	$191.80
Purchase #2	$193.64	12.534%	$217.9108	$217.91	$217.90	$217.90
Purchase #3	$196.34	10.739%	$217.425	$217.43	$217.45	$217.40
Purchase #4	$74.44	11.268%	$82.8279	$82.83	$82.85	$82.80
Purchase #5	$160.56	8.395%	$174.039	$174.04	$174.05	$174.00
Purchase #6	$143.75	7.394%	$154.3789	$154.38	$154.40	$154.40
Purchase #7	$59.55	12.322%	$66.8878	$66.89	$66.90	$66.90
7 purchase totals =	$1,005.53		$1,105.3000	$1,105.31	$1,105.40	$1,105.20