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	$86.84	9.562%	$95.1436	$95.14	$95.15	$95.10
Purchase #2	$198.55	13.529%	$225.4118	$225.41	$225.40	$225.40
Purchase #3	$185.82	7.552%	$199.8531	$199.85	$199.85	$199.90
Purchase #4	$159.46	5.489%	$168.2128	$168.21	$168.20	$168.20
Purchase #5	$11.76	3.466%	$12.1676	$12.17	$12.15	$12.20
Purchase #6	$143.55	11.217%	$159.652	$159.65	$159.65	$159.70
Purchase #7	$132.72	7.241%	$142.3303	$142.33	$142.35	$142.30
7 purchase totals =	$918.70		$1,002.7712	$1,002.76	$1,002.75	$1,002.80