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	$86.28	3.691%	$89.4646	$89.46	$89.45	$89.50
Purchase #2	$199.37	13.570%	$226.4245	$226.42	$226.40	$226.40
Purchase #3	$206.42	7.187%	$221.2554	$221.26	$221.25	$221.30
Purchase #4	$40.32	13.428%	$45.7342	$45.73	$45.75	$45.70
Purchase #5	$80.39	8.373%	$87.1211	$87.12	$87.10	$87.10
Purchase #6	$48.27	6.568%	$51.4404	$51.44	$51.45	$51.40
Purchase #7	$10.82	9.574%	$11.8559	$11.86	$11.85	$11.90
7 purchase totals =	$671.87		$733.2961	$733.29	$733.25	$733.30