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	$43.28	8.451%	$46.9376	$46.94	$46.95	$46.90
Purchase #2	$51.67	10.825%	$57.2633	$57.26	$57.25	$57.30
Purchase #3	$92.65	7.748%	$99.8285	$99.83	$99.85	$99.80
Purchase #4	$67.55	7.409%	$72.5548	$72.55	$72.55	$72.60
Purchase #5	$166.69	7.555%	$179.2834	$179.28	$179.30	$179.30
Purchase #6	$175.69	5.373%	$185.1298	$185.13	$185.15	$185.10
Purchase #7	$165.26	10.793%	$183.0965	$183.10	$183.10	$183.10
7 purchase totals =	$762.79		$824.0939	$824.09	$824.15	$824.10