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	$149.57	3.726%	$155.143	$155.14	$155.15	$155.10
Purchase #2	$40.66	7.587%	$43.7449	$43.74	$43.75	$43.70
Purchase #3	$184.76	8.719%	$200.8692	$200.87	$200.85	$200.90
Purchase #4	$95.65	4.616%	$100.0652	$100.07	$100.05	$100.10
Purchase #5	$238.51	6.595%	$254.2397	$254.24	$254.25	$254.20
Purchase #6	$29.30	8.256%	$31.719	$31.72	$31.70	$31.70
Purchase #7	$233.86	3.496%	$242.0357	$242.04	$242.05	$242.00
7 purchase totals =	$972.31		$1,027.8167	$1,027.82	$1,027.80	$1,027.70