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	$194.49	5.537%	$205.2589	$205.26	$205.25	$205.30
Purchase #2	$69.98	3.502%	$72.4307	$72.43	$72.45	$72.40
Purchase #3	$82.89	13.135%	$93.7776	$93.78	$93.80	$93.80
Purchase #4	$144.66	11.834%	$161.7791	$161.78	$161.80	$161.80
Purchase #5	$31.60	7.758%	$34.0515	$34.05	$34.05	$34.10
Purchase #6	$136.85	13.623%	$155.4931	$155.49	$155.50	$155.50
Purchase #7	$181.49	8.321%	$196.5918	$196.59	$196.60	$196.60
7 purchase totals =	$841.96		$919.3827	$919.38	$919.45	$919.50