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	$109.62	6.233%	$116.4526	$116.45	$116.45	$116.50
Purchase #2	$5.36	3.252%	$5.5343	$5.53	$5.55	$5.50
Purchase #3	$224.72	8.442%	$243.6909	$243.69	$243.70	$243.70
Purchase #4	$75.91	13.840%	$86.4159	$86.42	$86.40	$86.40
Purchase #5	$116.87	12.654%	$131.6587	$131.66	$131.65	$131.70
Purchase #6	$241.59	13.868%	$275.0937	$275.09	$275.10	$275.10
Purchase #7	$205.27	11.294%	$228.4532	$228.45	$228.45	$228.50
7 purchase totals =	$979.34		$1,087.2993	$1,087.29	$1,087.30	$1,087.40