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	$108.86	9.254%	$118.9339	$118.93	$118.95	$118.90
Purchase #2	$157.70	5.269%	$166.0092	$166.01	$166.00	$166.00
Purchase #3	$56.89	13.519%	$64.581	$64.58	$64.60	$64.60
Purchase #4	$7.71	6.207%	$8.1886	$8.19	$8.20	$8.20
Purchase #5	$173.33	3.551%	$179.4849	$179.48	$179.50	$179.50
Purchase #6	$154.64	9.460%	$169.2689	$169.27	$169.25	$169.30
Purchase #7	$69.75	12.601%	$78.5392	$78.54	$78.55	$78.50
7 purchase totals =	$728.88		$785.0057	$785.00	$785.05	$785.00