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	$138.25	10.181%	$152.3252	$152.33	$152.35	$152.30
Purchase #2	$58.53	4.681%	$61.2698	$61.27	$61.25	$61.30
Purchase #3	$81.51	6.308%	$86.6517	$86.65	$86.65	$86.70
Purchase #4	$126.44	6.164%	$134.2338	$134.23	$134.25	$134.20
Purchase #5	$190.89	13.112%	$215.9195	$215.92	$215.90	$215.90
Purchase #6	$107.55	6.720%	$114.7774	$114.78	$114.80	$114.80
Purchase #7	$238.56	4.439%	$249.1497	$249.15	$249.15	$249.10
7 purchase totals =	$941.73		$1,014.3271	$1,014.33	$1,014.35	$1,014.30