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	$114.82	9.618%	$125.8634	$125.86	$125.85	$125.90
Purchase #2	$205.48	3.388%	$212.4417	$212.44	$212.45	$212.40
Purchase #3	$101.34	3.340%	$104.7248	$104.72	$104.70	$104.70
Purchase #4	$165.52	10.862%	$183.4988	$183.50	$183.50	$183.50
Purchase #5	$110.59	11.581%	$123.3974	$123.40	$123.40	$123.40
Purchase #6	$51.71	3.134%	$53.3306	$53.33	$53.35	$53.30
Purchase #7	$158.93	6.475%	$169.2207	$169.22	$169.20	$169.20
7 purchase totals =	$908.39		$972.4774	$972.47	$972.45	$972.40