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	$98.95	12.440%	$111.2594	$111.26	$111.25	$111.30
Purchase #2	$212.58	12.128%	$238.3617	$238.36	$238.35	$238.40
Purchase #3	$156.80	5.594%	$165.5714	$165.57	$165.55	$165.60
Purchase #4	$222.80	13.658%	$253.23	$253.23	$253.25	$253.20
Purchase #5	$174.75	3.271%	$180.4661	$180.47	$180.45	$180.50
Purchase #6	$42.48	10.443%	$46.9162	$46.92	$46.90	$46.90
Purchase #7	$66.60	9.687%	$73.0515	$73.05	$73.05	$73.10
7 purchase totals =	$974.96		$1,068.8563	$1,068.86	$1,068.80	$1,069.00