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	$186.28	7.752%	$200.7204	$200.72	$200.70	$200.70
Purchase #2	$136.41	3.571%	$141.2812	$141.28	$141.30	$141.30
Purchase #3	$52.39	13.699%	$59.5669	$59.57	$59.55	$59.60
Purchase #4	$64.53	13.862%	$73.4751	$73.48	$73.50	$73.50
Purchase #5	$83.50	12.791%	$94.1805	$94.18	$94.20	$94.20
Purchase #6	$214.44	7.491%	$230.5037	$230.50	$230.50	$230.50
Purchase #7	$206.31	6.174%	$219.0476	$219.05	$219.05	$219.00
7 purchase totals =	$943.86		$1,018.7754	$1,018.78	$1,018.80	$1,018.80