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	$98.92	11.356%	$110.1534	$110.15	$110.15	$110.20
Purchase #2	$114.62	13.758%	$130.3894	$130.39	$130.40	$130.40
Purchase #3	$172.59	3.149%	$178.0249	$178.02	$178.00	$178.00
Purchase #4	$146.67	12.316%	$164.7339	$164.73	$164.75	$164.70
Purchase #5	$113.99	8.658%	$123.8593	$123.86	$123.85	$123.90
Purchase #6	$123.74	3.460%	$128.0214	$128.02	$128.00	$128.00
Purchase #7	$176.86	7.842%	$190.7294	$190.73	$190.75	$190.70
7 purchase totals =	$947.39		$1,025.9117	$1,025.90	$1,025.90	$1,025.90