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	$188.58	3.197%	$194.6089	$194.61	$194.60	$194.60
Purchase #2	$215.71	9.341%	$235.8595	$235.86	$235.85	$235.90
Purchase #3	$79.32	10.196%	$87.4075	$87.41	$87.40	$87.40
Purchase #4	$150.50	10.750%	$166.6788	$166.68	$166.70	$166.70
Purchase #5	$87.32	10.629%	$96.6012	$96.60	$96.60	$96.60
Purchase #6	$228.49	11.821%	$255.4998	$255.50	$255.50	$255.50
Purchase #7	$97.93	11.164%	$108.8629	$108.86	$108.85	$108.90
7 purchase totals =	$1,047.85		$1,145.5186	$1,145.52	$1,145.50	$1,145.60