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	$89.33	5.534%	$94.2735	$94.27	$94.25	$94.30
Purchase #2	$215.50	10.213%	$237.509	$237.51	$237.50	$237.50
Purchase #3	$191.73	11.766%	$214.289	$214.29	$214.30	$214.30
Purchase #4	$62.61	11.484%	$69.8001	$69.80	$69.80	$69.80
Purchase #5	$177.28	6.307%	$188.461	$188.46	$188.45	$188.50
Purchase #6	$187.85	4.510%	$196.322	$196.32	$196.30	$196.30
Purchase #7	$37.78	10.639%	$41.7994	$41.80	$41.80	$41.80
7 purchase totals =	$962.08		$1,042.4540	$1,042.45	$1,042.40	$1,042.50