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	$200.77	11.420%	$223.6979	$223.70	$223.70	$223.70
Purchase #2	$163.58	13.518%	$185.6927	$185.69	$185.70	$185.70
Purchase #3	$156.62	5.104%	$164.6139	$164.61	$164.60	$164.60
Purchase #4	$34.62	7.379%	$37.1746	$37.17	$37.15	$37.20
Purchase #5	$91.45	8.778%	$99.4775	$99.48	$99.50	$99.50
Purchase #6	$158.75	10.314%	$175.1235	$175.12	$175.10	$175.10
Purchase #7	$185.72	13.757%	$211.2695	$211.27	$211.25	$211.30
7 purchase totals =	$991.51		$1,097.0496	$1,097.04	$1,097.00	$1,097.10