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	$70.42	3.306%	$72.7481	$72.75	$72.75	$72.70
Purchase #2	$238.75	11.390%	$265.9436	$265.94	$265.95	$265.90
Purchase #3	$75.75	13.563%	$86.024	$86.02	$86.00	$86.00
Purchase #4	$120.26	10.521%	$132.9126	$132.91	$132.90	$132.90
Purchase #5	$226.38	3.537%	$234.3871	$234.39	$234.40	$234.40
Purchase #6	$88.73	13.300%	$100.5311	$100.53	$100.55	$100.50
Purchase #7	$159.67	7.142%	$171.0736	$171.07	$171.05	$171.10
7 purchase totals =	$979.96		$1,063.6201	$1,063.61	$1,063.60	$1,063.50