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	$219.90	11.730%	$245.6943	$245.69	$245.70	$245.70
Purchase #2	$214.71	4.856%	$225.1363	$225.14	$225.15	$225.10
Purchase #3	$81.85	9.168%	$89.354	$89.35	$89.35	$89.40
Purchase #4	$83.96	6.484%	$89.404	$89.40	$89.40	$89.40
Purchase #5	$147.33	3.677%	$152.7473	$152.75	$152.75	$152.70
Purchase #6	$205.54	9.630%	$225.3335	$225.33	$225.35	$225.30
Purchase #7	$63.71	3.339%	$65.8373	$65.84	$65.85	$65.80
7 purchase totals =	$1,017.00		$1,093.5067	$1,093.50	$1,093.55	$1,093.40