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	$113.87	10.533%	$125.8639	$125.86	$125.85	$125.90
Purchase #2	$69.92	11.743%	$78.1307	$78.13	$78.15	$78.10
Purchase #3	$69.85	10.748%	$77.3575	$77.36	$77.35	$77.40
Purchase #4	$171.54	9.475%	$187.7934	$187.79	$187.80	$187.80
Purchase #5	$126.72	10.131%	$139.558	$139.56	$139.55	$139.60
Purchase #6	$162.66	13.787%	$185.0859	$185.09	$185.10	$185.10
Purchase #7	$233.67	12.498%	$262.8741	$262.87	$262.85	$262.90
7 purchase totals =	$948.23		$1,056.6635	$1,056.66	$1,056.65	$1,056.80