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	$236.65	7.213%	$253.7196	$253.72	$253.70	$253.70
Purchase #2	$228.90	4.239%	$238.6031	$238.60	$238.60	$238.60
Purchase #3	$74.93	13.795%	$85.2666	$85.27	$85.25	$85.30
Purchase #4	$83.66	9.343%	$91.4764	$91.48	$91.50	$91.50
Purchase #5	$188.57	4.294%	$196.6672	$196.67	$196.65	$196.70
Purchase #6	$74.29	12.802%	$83.8006	$83.80	$83.80	$83.80
Purchase #7	$205.47	3.353%	$212.3594	$212.36	$212.35	$212.40
7 purchase totals =	$1,092.47		$1,161.8929	$1,161.90	$1,161.85	$1,162.00