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	$188.86	10.684%	$209.0378	$209.04	$209.05	$209.00
Purchase #2	$104.82	11.109%	$116.4645	$116.46	$116.45	$116.50
Purchase #3	$239.59	4.395%	$250.12	$250.12	$250.10	$250.10
Purchase #4	$237.68	10.257%	$262.0588	$262.06	$262.05	$262.10
Purchase #5	$133.89	13.169%	$151.522	$151.52	$151.50	$151.50
Purchase #6	$238.50	5.447%	$251.4911	$251.49	$251.50	$251.50
Purchase #7	$150.86	6.320%	$160.3944	$160.39	$160.40	$160.40
7 purchase totals =	$1,294.20		$1,401.0886	$1,401.08	$1,401.05	$1,401.10