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	$212.65	8.438%	$230.5934	$230.59	$230.60	$230.60
Purchase #2	$199.43	3.837%	$207.0821	$207.08	$207.10	$207.10
Purchase #3	$73.25	13.761%	$83.3299	$83.33	$83.35	$83.30
Purchase #4	$57.34	3.126%	$59.1324	$59.13	$59.15	$59.10
Purchase #5	$161.50	6.698%	$172.3173	$172.32	$172.30	$172.30
Purchase #6	$194.89	7.808%	$210.107	$210.11	$210.10	$210.10
Purchase #7	$81.27	5.659%	$85.8691	$85.87	$85.85	$85.90
7 purchase totals =	$980.33		$1,048.4312	$1,048.43	$1,048.45	$1,048.40