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	$174.51	9.768%	$191.5561	$191.56	$191.55	$191.60
Purchase #2	$10.59	4.784%	$11.0966	$11.10	$11.10	$11.10
Purchase #3	$37.26	8.863%	$40.5624	$40.56	$40.55	$40.60
Purchase #4	$154.50	10.168%	$170.2096	$170.21	$170.20	$170.20
Purchase #5	$199.65	7.761%	$215.1448	$215.14	$215.15	$215.10
Purchase #6	$40.35	5.405%	$42.5309	$42.53	$42.55	$42.50
Purchase #7	$40.46	8.655%	$43.9618	$43.96	$43.95	$44.00
7 purchase totals =	$657.32		$715.0622	$715.06	$715.05	$715.10