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	$207.60	7.710%	$223.606	$223.61	$223.60	$223.60
Purchase #2	$153.88	8.751%	$167.346	$167.35	$167.35	$167.30
Purchase #3	$169.82	5.433%	$179.0463	$179.05	$179.05	$179.00
Purchase #4	$48.33	10.157%	$53.2389	$53.24	$53.25	$53.20
Purchase #5	$183.39	9.483%	$200.7809	$200.78	$200.80	$200.80
Purchase #6	$39.63	4.693%	$41.4898	$41.49	$41.50	$41.50
Purchase #7	$194.26	13.371%	$220.2345	$220.23	$220.25	$220.20
7 purchase totals =	$996.91		$1,085.7424	$1,085.75	$1,085.80	$1,085.60