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	$205.70	13.435%	$233.3358	$233.34	$233.35	$233.30
Purchase #2	$7.31	8.250%	$7.9131	$7.91	$7.90	$7.90
Purchase #3	$208.98	3.164%	$215.5921	$215.59	$215.60	$215.60
Purchase #4	$117.46	5.251%	$123.6278	$123.63	$123.65	$123.60
Purchase #5	$86.88	13.373%	$98.4985	$98.50	$98.50	$98.50
Purchase #6	$102.76	13.863%	$117.0056	$117.01	$117.00	$117.00
Purchase #7	$217.70	4.408%	$227.2962	$227.30	$227.30	$227.30
7 purchase totals =	$946.79		$1,023.2691	$1,023.28	$1,023.30	$1,023.20