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	$82.64	8.508%	$89.671	$89.67	$89.65	$89.70
Purchase #2	$93.59	7.616%	$100.7178	$100.72	$100.70	$100.70
Purchase #3	$139.64	10.776%	$154.6876	$154.69	$154.70	$154.70
Purchase #4	$205.46	7.648%	$221.1736	$221.17	$221.15	$221.20
Purchase #5	$179.73	5.129%	$188.9484	$188.95	$188.95	$188.90
Purchase #6	$128.53	9.756%	$141.0694	$141.07	$141.05	$141.10
Purchase #7	$135.94	13.869%	$154.7935	$154.79	$154.80	$154.80
7 purchase totals =	$965.53		$1,051.0613	$1,051.06	$1,051.00	$1,051.10