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	$179.40	8.545%	$194.7297	$194.73	$194.75	$194.70
Purchase #2	$121.59	9.557%	$133.2104	$133.21	$133.20	$133.20
Purchase #3	$155.76	4.421%	$162.6461	$162.65	$162.65	$162.60
Purchase #4	$89.50	10.413%	$98.8196	$98.82	$98.80	$98.80
Purchase #5	$63.32	6.628%	$67.5168	$67.52	$67.50	$67.50
Purchase #6	$183.33	3.839%	$190.368	$190.37	$190.35	$190.40
Purchase #7	$158.57	12.294%	$178.0646	$178.06	$178.05	$178.10
7 purchase totals =	$951.47		$1,025.3552	$1,025.36	$1,025.30	$1,025.30