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	$98.36	3.157%	$101.4652	$101.47	$101.45	$101.50
Purchase #2	$66.47	9.705%	$72.9209	$72.92	$72.90	$72.90
Purchase #3	$210.64	12.120%	$236.1696	$236.17	$236.15	$236.20
Purchase #4	$236.94	8.145%	$256.2388	$256.24	$256.25	$256.20
Purchase #5	$112.51	10.666%	$124.5103	$124.51	$124.50	$124.50
Purchase #6	$139.86	8.154%	$151.2642	$151.26	$151.25	$151.30
Purchase #7	$137.95	11.113%	$153.2804	$153.28	$153.30	$153.30
7 purchase totals =	$1,002.73		$1,095.8494	$1,095.85	$1,095.80	$1,095.90