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	$216.60	8.740%	$235.5308	$235.53	$235.55	$235.50
Purchase #2	$144.33	5.274%	$151.942	$151.94	$151.95	$151.90
Purchase #3	$54.94	8.731%	$59.7368	$59.74	$59.75	$59.70
Purchase #4	$72.80	3.153%	$75.0954	$75.10	$75.10	$75.10
Purchase #5	$53.51	11.645%	$59.7412	$59.74	$59.75	$59.70
Purchase #6	$221.30	11.367%	$246.4552	$246.46	$246.45	$246.50
Purchase #7	$136.68	4.576%	$142.9345	$142.93	$142.95	$142.90
7 purchase totals =	$900.16		$971.4359	$971.44	$971.50	$971.30