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	$223.72	8.115%	$241.8749	$241.87	$241.85	$241.90
Purchase #2	$35.71	4.167%	$37.198	$37.20	$37.20	$37.20
Purchase #3	$110.75	12.345%	$124.4221	$124.42	$124.40	$124.40
Purchase #4	$175.54	5.578%	$185.3316	$185.33	$185.35	$185.30
Purchase #5	$24.45	4.339%	$25.5109	$25.51	$25.50	$25.50
Purchase #6	$158.64	7.348%	$170.2969	$170.30	$170.30	$170.30
Purchase #7	$9.75	7.724%	$10.5031	$10.50	$10.50	$10.50
7 purchase totals =	$738.56		$795.1375	$795.13	$795.10	$795.10