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	$56.38	9.700%	$61.8489	$61.85	$61.85	$61.80
Purchase #2	$195.93	7.141%	$209.9214	$209.92	$209.90	$209.90
Purchase #3	$189.85	12.611%	$213.792	$213.79	$213.80	$213.80
Purchase #4	$248.40	4.602%	$259.8314	$259.83	$259.85	$259.80
Purchase #5	$96.34	4.426%	$100.604	$100.60	$100.60	$100.60
Purchase #6	$216.98	12.247%	$243.5535	$243.55	$243.55	$243.60
Purchase #7	$13.47	9.290%	$14.7214	$14.72	$14.70	$14.70
7 purchase totals =	$1,017.35		$1,104.2726	$1,104.26	$1,104.25	$1,104.20