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	$209.52	13.806%	$238.4463	$238.45	$238.45	$238.40
Purchase #2	$149.65	11.784%	$167.2848	$167.28	$167.30	$167.30
Purchase #3	$20.77	4.513%	$21.7074	$21.71	$21.70	$21.70
Purchase #4	$189.95	6.652%	$202.5855	$202.59	$202.60	$202.60
Purchase #5	$164.93	3.437%	$170.5986	$170.60	$170.60	$170.60
Purchase #6	$19.78	3.499%	$20.4721	$20.47	$20.45	$20.50
Purchase #7	$186.38	4.701%	$195.1417	$195.14	$195.15	$195.10
7 purchase totals =	$940.98		$1,016.2364	$1,016.24	$1,016.25	$1,016.20