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	$190.93	11.740%	$213.3452	$213.35	$213.35	$213.30
Purchase #2	$228.50	12.361%	$256.7449	$256.74	$256.75	$256.70
Purchase #3	$52.52	13.219%	$59.4626	$59.46	$59.45	$59.50
Purchase #4	$116.92	13.108%	$132.2459	$132.25	$132.25	$132.20
Purchase #5	$167.85	11.209%	$186.6643	$186.66	$186.65	$186.70
Purchase #6	$217.81	10.485%	$240.6474	$240.65	$240.65	$240.60
Purchase #7	$82.64	10.675%	$91.4618	$91.46	$91.45	$91.50
7 purchase totals =	$1,057.17		$1,180.5721	$1,180.57	$1,180.55	$1,180.50