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	$59.66	4.859%	$62.5589	$62.56	$62.55	$62.60
Purchase #2	$162.61	10.283%	$179.3312	$179.33	$179.35	$179.30
Purchase #3	$172.46	10.245%	$190.1285	$190.13	$190.15	$190.10
Purchase #4	$49.36	5.791%	$52.2184	$52.22	$52.20	$52.20
Purchase #5	$218.50	7.698%	$235.3201	$235.32	$235.30	$235.30
Purchase #6	$196.38	10.765%	$217.5203	$217.52	$217.50	$217.50
Purchase #7	$66.94	9.383%	$73.221	$73.22	$73.20	$73.20
7 purchase totals =	$925.91		$1,010.2984	$1,010.30	$1,010.25	$1,010.20