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	$212.56	7.465%	$228.4276	$228.43	$228.45	$228.40
Purchase #2	$239.44	9.325%	$261.7678	$261.77	$261.75	$261.80
Purchase #3	$54.86	4.843%	$57.5169	$57.52	$57.50	$57.50
Purchase #4	$66.50	8.505%	$72.1558	$72.16	$72.15	$72.20
Purchase #5	$197.94	11.187%	$220.0835	$220.08	$220.10	$220.10
Purchase #6	$211.48	10.589%	$233.8736	$233.87	$233.85	$233.90
Purchase #7	$155.72	7.839%	$167.9269	$167.93	$167.95	$167.90
7 purchase totals =	$1,138.50		$1,241.7521	$1,241.76	$1,241.75	$1,241.80