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	$198.55	4.769%	$208.0188	$208.02	$208.00	$208.00
Purchase #2	$161.48	7.332%	$173.3197	$173.32	$173.30	$173.30
Purchase #3	$81.43	10.291%	$89.81	$89.81	$89.80	$89.80
Purchase #4	$143.60	4.366%	$149.8696	$149.87	$149.85	$149.90
Purchase #5	$33.94	10.335%	$37.4477	$37.45	$37.45	$37.40
Purchase #6	$211.65	7.378%	$227.2655	$227.27	$227.25	$227.30
Purchase #7	$154.66	4.523%	$161.6553	$161.66	$161.65	$161.70
7 purchase totals =	$985.31		$1,047.3866	$1,047.40	$1,047.30	$1,047.40