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	$216.82	7.672%	$233.4544	$233.45	$233.45	$233.50
Purchase #2	$5.26	4.835%	$5.5143	$5.51	$5.50	$5.50
Purchase #3	$102.83	6.652%	$109.6703	$109.67	$109.65	$109.70
Purchase #4	$14.38	4.278%	$14.9952	$15.00	$15.00	$15.00
Purchase #5	$196.44	13.814%	$223.5762	$223.58	$223.60	$223.60
Purchase #6	$12.33	4.222%	$12.8506	$12.85	$12.85	$12.90
Purchase #7	$14.35	6.109%	$15.2266	$15.23	$15.25	$15.20
7 purchase totals =	$562.41		$615.2876	$615.29	$615.30	$615.40