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	$184.94	6.263%	$196.5228	$196.52	$196.50	$196.50
Purchase #2	$71.98	8.289%	$77.9464	$77.95	$77.95	$77.90
Purchase #3	$235.78	5.338%	$248.3659	$248.37	$248.35	$248.40
Purchase #4	$42.38	8.376%	$45.9297	$45.93	$45.95	$45.90
Purchase #5	$165.78	13.324%	$187.8685	$187.87	$187.85	$187.90
Purchase #6	$84.48	6.346%	$89.8411	$89.84	$89.85	$89.80
Purchase #7	$153.86	5.145%	$161.7761	$161.78	$161.80	$161.80
7 purchase totals =	$939.20		$1,008.2505	$1,008.26	$1,008.25	$1,008.20