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	$216.53	7.643%	$233.0794	$233.08	$233.10	$233.10
Purchase #2	$33.51	10.309%	$36.9645	$36.96	$36.95	$37.00
Purchase #3	$47.69	9.631%	$52.283	$52.28	$52.30	$52.30
Purchase #4	$10.49	9.777%	$11.5156	$11.52	$11.50	$11.50
Purchase #5	$59.65	12.387%	$67.0388	$67.04	$67.05	$67.00
Purchase #6	$145.34	3.263%	$150.0824	$150.08	$150.10	$150.10
Purchase #7	$245.56	7.202%	$263.2452	$263.25	$263.25	$263.20
7 purchase totals =	$758.77		$814.2089	$814.21	$814.25	$814.20