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	$115.87	10.178%	$127.6632	$127.66	$127.65	$127.70
Purchase #2	$136.66	6.748%	$145.8818	$145.88	$145.90	$145.90
Purchase #3	$69.63	3.506%	$72.0712	$72.07	$72.05	$72.10
Purchase #4	$210.91	3.272%	$217.811	$217.81	$217.80	$217.80
Purchase #5	$237.88	12.804%	$268.3382	$268.34	$268.35	$268.30
Purchase #6	$50.44	6.625%	$53.7817	$53.78	$53.80	$53.80
Purchase #7	$131.42	13.123%	$148.6662	$148.67	$148.65	$148.70
7 purchase totals =	$952.81		$1,034.2133	$1,034.21	$1,034.20	$1,034.30