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	$172.58	13.548%	$195.9611	$195.96	$195.95	$196.00
Purchase #2	$223.86	11.476%	$249.5502	$249.55	$249.55	$249.60
Purchase #3	$88.86	8.616%	$96.5162	$96.52	$96.50	$96.50
Purchase #4	$155.80	12.497%	$175.2703	$175.27	$175.25	$175.30
Purchase #5	$58.56	3.490%	$60.6037	$60.60	$60.60	$60.60
Purchase #6	$145.80	7.324%	$156.4784	$156.48	$156.50	$156.50
Purchase #7	$117.66	12.619%	$132.5075	$132.51	$132.50	$132.50
7 purchase totals =	$963.12		$1,066.8874	$1,066.89	$1,066.85	$1,067.00