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	$78.40	9.173%	$85.5916	$85.59	$85.60	$85.60
Purchase #2	$95.32	4.424%	$99.537	$99.54	$99.55	$99.50
Purchase #3	$85.75	9.741%	$94.1029	$94.10	$94.10	$94.10
Purchase #4	$159.86	11.431%	$178.1336	$178.13	$178.15	$178.10
Purchase #5	$87.95	8.756%	$95.6509	$95.65	$95.65	$95.70
Purchase #6	$242.85	4.309%	$253.3144	$253.31	$253.30	$253.30
Purchase #7	$195.57	13.869%	$222.6936	$222.69	$222.70	$222.70
7 purchase totals =	$945.70		$1,029.0240	$1,029.01	$1,029.05	$1,029.00