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	$84.48	8.223%	$91.4268	$91.43	$91.45	$91.40
Purchase #2	$45.44	6.855%	$48.5549	$48.55	$48.55	$48.60
Purchase #3	$68.66	6.569%	$73.1703	$73.17	$73.15	$73.20
Purchase #4	$213.98	4.583%	$223.7867	$223.79	$223.80	$223.80
Purchase #5	$76.59	11.182%	$85.1543	$85.15	$85.15	$85.20
Purchase #6	$248.71	11.195%	$276.5531	$276.55	$276.55	$276.60
Purchase #7	$206.82	5.830%	$218.8776	$218.88	$218.90	$218.90
7 purchase totals =	$944.68		$1,017.5237	$1,017.52	$1,017.55	$1,017.70