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	$58.41	5.761%	$61.775	$61.78	$61.80	$61.80
Purchase #2	$50.92	5.368%	$53.6534	$53.65	$53.65	$53.70
Purchase #3	$69.76	4.360%	$72.8015	$72.80	$72.80	$72.80
Purchase #4	$100.41	13.300%	$113.7645	$113.76	$113.75	$113.80
Purchase #5	$193.66	5.498%	$204.3074	$204.31	$204.30	$204.30
Purchase #6	$39.97	6.708%	$42.6512	$42.65	$42.65	$42.70
Purchase #7	$92.90	12.838%	$104.8265	$104.83	$104.85	$104.80
7 purchase totals =	$606.03		$653.7795	$653.78	$653.80	$653.90