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	$208.67	9.701%	$228.9131	$228.91	$228.90	$228.90
Purchase #2	$245.63	4.169%	$255.8703	$255.87	$255.85	$255.90
Purchase #3	$17.82	3.218%	$18.3934	$18.39	$18.40	$18.40
Purchase #4	$103.82	6.468%	$110.5351	$110.54	$110.55	$110.50
Purchase #5	$225.94	8.681%	$245.5539	$245.55	$245.55	$245.60
Purchase #6	$31.33	3.696%	$32.488	$32.49	$32.50	$32.50
Purchase #7	$151.36	13.146%	$171.2578	$171.26	$171.25	$171.30
7 purchase totals =	$984.57		$1,063.0116	$1,063.01	$1,063.00	$1,063.10