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	$84.72	13.285%	$95.9751	$95.98	$96.00	$96.00
Purchase #2	$244.53	7.241%	$262.2364	$262.24	$262.25	$262.20
Purchase #3	$198.81	9.374%	$217.4464	$217.45	$217.45	$217.40
Purchase #4	$56.86	5.217%	$59.8264	$59.83	$59.85	$59.80
Purchase #5	$84.27	13.415%	$95.5748	$95.57	$95.55	$95.60
Purchase #6	$105.34	6.385%	$112.066	$112.07	$112.05	$112.10
Purchase #7	$92.77	7.563%	$99.7862	$99.79	$99.80	$99.80
7 purchase totals =	$867.30		$942.9113	$942.93	$942.95	$942.90