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	$182.97	7.406%	$196.5208	$196.52	$196.50	$196.50
Purchase #2	$45.64	3.202%	$47.1014	$47.10	$47.10	$47.10
Purchase #3	$86.71	8.484%	$94.0665	$94.07	$94.05	$94.10
Purchase #4	$145.71	9.172%	$159.0745	$159.07	$159.05	$159.10
Purchase #5	$23.39	3.564%	$24.2236	$24.22	$24.20	$24.20
Purchase #6	$57.56	3.155%	$59.376	$59.38	$59.40	$59.40
Purchase #7	$122.56	4.499%	$128.074	$128.07	$128.05	$128.10
7 purchase totals =	$664.54		$708.4368	$708.43	$708.35	$708.50