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	$103.30	9.819%	$113.443	$113.44	$113.45	$113.40
Purchase #2	$47.79	10.676%	$52.8921	$52.89	$52.90	$52.90
Purchase #3	$177.55	10.522%	$196.2318	$196.23	$196.25	$196.20
Purchase #4	$195.29	7.629%	$210.1887	$210.19	$210.20	$210.20
Purchase #5	$235.75	8.777%	$256.4418	$256.44	$256.45	$256.40
Purchase #6	$173.57	9.327%	$189.7589	$189.76	$189.75	$189.80
Purchase #7	$128.47	13.617%	$145.9638	$145.96	$145.95	$146.00
7 purchase totals =	$1,061.72		$1,164.9201	$1,164.91	$1,164.95	$1,164.90