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	$193.42	13.317%	$219.1777	$219.18	$219.20	$219.20
Purchase #2	$203.26	11.114%	$225.8503	$225.85	$225.85	$225.90
Purchase #3	$33.59	5.384%	$35.3985	$35.40	$35.40	$35.40
Purchase #4	$42.62	11.203%	$47.3947	$47.39	$47.40	$47.40
Purchase #5	$25.42	8.588%	$27.6031	$27.60	$27.60	$27.60
Purchase #6	$233.51	10.655%	$258.3905	$258.39	$258.40	$258.40
Purchase #7	$209.58	11.407%	$233.4868	$233.49	$233.50	$233.50
7 purchase totals =	$941.40		$1,047.3016	$1,047.30	$1,047.35	$1,047.40