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	$212.41	11.455%	$236.7416	$236.74	$236.75	$236.70
Purchase #2	$198.30	3.815%	$205.8651	$205.87	$205.85	$205.90
Purchase #3	$59.92	6.684%	$63.9251	$63.93	$63.95	$63.90
Purchase #4	$247.71	6.627%	$264.1257	$264.13	$264.15	$264.10
Purchase #5	$12.86	13.191%	$14.5564	$14.56	$14.55	$14.60
Purchase #6	$241.30	8.410%	$261.5933	$261.59	$261.60	$261.60
Purchase #7	$42.78	13.585%	$48.5917	$48.59	$48.60	$48.60
7 purchase totals =	$1,015.28		$1,095.3989	$1,095.41	$1,095.45	$1,095.40