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	$68.41	7.762%	$73.72	$73.72	$73.70	$73.70
Purchase #2	$29.41	7.477%	$31.609	$31.61	$31.60	$31.60
Purchase #3	$111.89	3.233%	$115.5074	$115.51	$115.50	$115.50
Purchase #4	$244.57	9.197%	$267.0631	$267.06	$267.05	$267.10
Purchase #5	$127.81	7.248%	$137.0737	$137.07	$137.05	$137.10
Purchase #6	$215.81	12.605%	$243.0129	$243.01	$243.00	$243.00
Purchase #7	$211.73	10.301%	$233.5403	$233.54	$233.55	$233.50
7 purchase totals =	$1,009.63		$1,101.5264	$1,101.52	$1,101.45	$1,101.50