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	$64.95	11.349%	$72.3212	$72.32	$72.30	$72.30
Purchase #2	$73.78	13.280%	$83.578	$83.58	$83.60	$83.60
Purchase #3	$109.89	5.556%	$115.9955	$116.00	$116.00	$116.00
Purchase #4	$135.50	11.730%	$151.3942	$151.39	$151.40	$151.40
Purchase #5	$23.62	12.299%	$26.525	$26.53	$26.55	$26.50
Purchase #6	$199.58	8.173%	$215.8917	$215.89	$215.90	$215.90
Purchase #7	$53.27	6.470%	$56.7166	$56.72	$56.70	$56.70
7 purchase totals =	$660.59		$722.4222	$722.43	$722.45	$722.40