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	$194.51	8.804%	$211.6347	$211.63	$211.65	$211.60
Purchase #2	$210.98	10.822%	$233.8123	$233.81	$233.80	$233.80
Purchase #3	$13.59	4.429%	$14.1919	$14.19	$14.20	$14.20
Purchase #4	$120.36	7.303%	$129.1499	$129.15	$129.15	$129.10
Purchase #5	$150.89	4.824%	$158.1689	$158.17	$158.15	$158.20
Purchase #6	$172.53	11.544%	$192.4469	$192.45	$192.45	$192.40
Purchase #7	$141.31	3.154%	$145.7669	$145.77	$145.75	$145.80
7 purchase totals =	$1,004.17		$1,085.1715	$1,085.17	$1,085.15	$1,085.10