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	$196.35	7.108%	$210.3066	$210.31	$210.30	$210.30
Purchase #2	$86.36	11.188%	$96.022	$96.02	$96.00	$96.00
Purchase #3	$11.47	11.342%	$12.7709	$12.77	$12.75	$12.80
Purchase #4	$60.90	10.846%	$67.5052	$67.51	$67.50	$67.50
Purchase #5	$151.83	11.121%	$168.715	$168.72	$168.70	$168.70
Purchase #6	$68.88	3.516%	$71.3018	$71.30	$71.30	$71.30
Purchase #7	$120.64	5.123%	$126.8204	$126.82	$126.80	$126.80
7 purchase totals =	$696.43		$753.4419	$753.45	$753.35	$753.40