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	$208.71	11.856%	$233.4547	$233.45	$233.45	$233.50
Purchase #2	$220.35	11.412%	$245.4963	$245.50	$245.50	$245.50
Purchase #3	$125.30	4.394%	$130.8057	$130.81	$130.80	$130.80
Purchase #4	$145.77	7.471%	$156.6605	$156.66	$156.65	$156.70
Purchase #5	$158.41	9.590%	$173.6015	$173.60	$173.60	$173.60
Purchase #6	$42.81	3.632%	$44.3649	$44.36	$44.35	$44.40
Purchase #7	$27.44	8.818%	$29.8597	$29.86	$29.85	$29.90
7 purchase totals =	$928.79		$1,014.2433	$1,014.24	$1,014.20	$1,014.40