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	$112.86	11.191%	$125.4902	$125.49	$125.50	$125.50
Purchase #2	$189.97	11.683%	$212.1642	$212.16	$212.15	$212.20
Purchase #3	$13.61	5.458%	$14.3528	$14.35	$14.35	$14.40
Purchase #4	$164.60	8.222%	$178.1334	$178.13	$178.15	$178.10
Purchase #5	$100.41	9.274%	$109.722	$109.72	$109.70	$109.70
Purchase #6	$120.25	13.332%	$136.2817	$136.28	$136.30	$136.30
Purchase #7	$106.56	4.271%	$111.1112	$111.11	$111.10	$111.10
7 purchase totals =	$808.26		$887.2555	$887.24	$887.25	$887.30