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	$191.55	10.845%	$212.3236	$212.32	$212.30	$212.30
Purchase #2	$116.28	5.515%	$122.6928	$122.69	$122.70	$122.70
Purchase #3	$17.48	8.166%	$18.9074	$18.91	$18.90	$18.90
Purchase #4	$46.28	10.692%	$51.2283	$51.23	$51.25	$51.20
Purchase #5	$5.81	12.616%	$6.543	$6.54	$6.55	$6.50
Purchase #6	$177.54	10.415%	$196.0308	$196.03	$196.05	$196.00
Purchase #7	$112.57	10.675%	$124.5868	$124.59	$124.60	$124.60
7 purchase totals =	$667.51		$732.3127	$732.31	$732.35	$732.20