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	$213.81	10.135%	$235.4796	$235.48	$235.50	$235.50
Purchase #2	$76.25	6.405%	$81.1338	$81.13	$81.15	$81.10
Purchase #3	$69.26	13.579%	$78.6648	$78.66	$78.65	$78.70
Purchase #4	$165.65	13.769%	$188.4583	$188.46	$188.45	$188.50
Purchase #5	$203.73	8.720%	$221.4953	$221.50	$221.50	$221.50
Purchase #6	$181.30	9.420%	$198.3785	$198.38	$198.40	$198.40
Purchase #7	$18.86	7.586%	$20.2907	$20.29	$20.30	$20.30
7 purchase totals =	$928.86		$1,023.9010	$1,023.90	$1,023.95	$1,024.00