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	$184.63	13.495%	$209.5458	$209.55	$209.55	$209.50
Purchase #2	$19.86	3.763%	$20.6073	$20.61	$20.60	$20.60
Purchase #3	$34.39	4.830%	$36.051	$36.05	$36.05	$36.10
Purchase #4	$218.85	10.445%	$241.7089	$241.71	$241.70	$241.70
Purchase #5	$104.78	4.376%	$109.3652	$109.37	$109.35	$109.40
Purchase #6	$227.50	11.481%	$253.6193	$253.62	$253.60	$253.60
Purchase #7	$37.96	6.108%	$40.2786	$40.28	$40.30	$40.30
7 purchase totals =	$827.97		$911.1761	$911.19	$911.15	$911.20