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	$84.85	12.644%	$95.5784	$95.58	$95.60	$95.60
Purchase #2	$14.67	6.695%	$15.6522	$15.65	$15.65	$15.70
Purchase #3	$226.43	6.391%	$240.9011	$240.90	$240.90	$240.90
Purchase #4	$198.25	3.462%	$205.1134	$205.11	$205.10	$205.10
Purchase #5	$60.63	11.489%	$67.5958	$67.60	$67.60	$67.60
Purchase #6	$234.27	3.596%	$242.6943	$242.69	$242.70	$242.70
Purchase #7	$210.76	10.734%	$233.383	$233.38	$233.40	$233.40
7 purchase totals =	$1,029.86		$1,100.9182	$1,100.91	$1,100.95	$1,101.00