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	$205.29	13.822%	$233.6652	$233.67	$233.65	$233.70
Purchase #2	$166.77	4.658%	$174.5381	$174.54	$174.55	$174.50
Purchase #3	$233.34	8.457%	$253.0736	$253.07	$253.05	$253.10
Purchase #4	$44.79	7.658%	$48.22	$48.22	$48.20	$48.20
Purchase #5	$242.76	8.238%	$262.7586	$262.76	$262.75	$262.80
Purchase #6	$142.93	13.476%	$162.1912	$162.19	$162.20	$162.20
Purchase #7	$55.56	10.872%	$61.6005	$61.60	$61.60	$61.60
7 purchase totals =	$1,091.44		$1,196.0472	$1,196.05	$1,196.00	$1,196.10