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	$145.89	11.631%	$162.8585	$162.86	$162.85	$162.90
Purchase #2	$249.63	11.136%	$277.4288	$277.43	$277.45	$277.40
Purchase #3	$93.83	3.338%	$96.962	$96.96	$96.95	$97.00
Purchase #4	$15.52	9.549%	$17.002	$17.00	$17.00	$17.00
Purchase #5	$176.61	8.159%	$191.0196	$191.02	$191.00	$191.00
Purchase #6	$173.94	5.501%	$183.5084	$183.51	$183.50	$183.50
Purchase #7	$113.86	11.761%	$127.2511	$127.25	$127.25	$127.30
7 purchase totals =	$969.28		$1,056.0304	$1,056.03	$1,056.00	$1,056.10