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	$172.33	13.819%	$196.1443	$196.14	$196.15	$196.10
Purchase #2	$190.39	12.812%	$214.7828	$214.78	$214.80	$214.80
Purchase #3	$195.54	8.447%	$212.0573	$212.06	$212.05	$212.10
Purchase #4	$250.65	5.172%	$263.6136	$263.61	$263.60	$263.60
Purchase #5	$42.51	11.511%	$47.4033	$47.40	$47.40	$47.40
Purchase #6	$108.54	3.726%	$112.5842	$112.58	$112.60	$112.60
Purchase #7	$62.30	5.781%	$65.9016	$65.90	$65.90	$65.90
7 purchase totals =	$1,022.26		$1,112.4871	$1,112.47	$1,112.50	$1,112.50