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	$191.82	9.418%	$209.8856	$209.89	$209.90	$209.90
Purchase #2	$206.55	8.427%	$223.956	$223.96	$223.95	$224.00
Purchase #3	$212.49	9.830%	$233.3778	$233.38	$233.40	$233.40
Purchase #4	$230.39	8.296%	$249.5032	$249.50	$249.50	$249.50
Purchase #5	$40.96	13.802%	$46.6133	$46.61	$46.60	$46.60
Purchase #6	$27.90	3.350%	$28.8347	$28.83	$28.85	$28.80
Purchase #7	$56.98	9.726%	$62.5219	$62.52	$62.50	$62.50
7 purchase totals =	$967.09		$1,054.6925	$1,054.69	$1,054.70	$1,054.70