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	$79.50	7.493%	$85.4569	$85.46	$85.45	$85.50
Purchase #2	$141.80	7.223%	$152.0422	$152.04	$152.05	$152.00
Purchase #3	$101.66	10.687%	$112.5244	$112.52	$112.50	$112.50
Purchase #4	$213.30	6.138%	$226.3924	$226.39	$226.40	$226.40
Purchase #5	$98.50	6.557%	$104.9586	$104.96	$104.95	$105.00
Purchase #6	$137.57	11.381%	$153.2268	$153.23	$153.25	$153.20
Purchase #7	$212.81	3.348%	$219.9349	$219.93	$219.95	$219.90
7 purchase totals =	$985.14		$1,054.5362	$1,054.53	$1,054.55	$1,054.50