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	$181.77	5.415%	$191.6128	$191.61	$191.60	$191.60
Purchase #2	$190.38	13.456%	$215.9975	$216.00	$216.00	$216.00
Purchase #3	$195.55	7.747%	$210.6993	$210.70	$210.70	$210.70
Purchase #4	$131.92	9.799%	$144.8468	$144.85	$144.85	$144.80
Purchase #5	$49.58	13.294%	$56.1712	$56.17	$56.15	$56.20
Purchase #6	$92.43	11.275%	$102.8515	$102.85	$102.85	$102.90
Purchase #7	$122.95	6.618%	$131.0868	$131.09	$131.10	$131.10
7 purchase totals =	$964.58		$1,053.2659	$1,053.27	$1,053.25	$1,053.30