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	$62.27	7.721%	$67.0779	$67.08	$67.10	$67.10
Purchase #2	$148.37	9.752%	$162.839	$162.84	$162.85	$162.80
Purchase #3	$219.33	4.561%	$229.3336	$229.33	$229.35	$229.30
Purchase #4	$92.27	9.355%	$100.9019	$100.90	$100.90	$100.90
Purchase #5	$55.93	11.625%	$62.4319	$62.43	$62.45	$62.40
Purchase #6	$243.51	5.452%	$256.7862	$256.79	$256.80	$256.80
Purchase #7	$62.55	6.548%	$66.6458	$66.65	$66.65	$66.60
7 purchase totals =	$884.23		$946.0163	$946.02	$946.10	$945.90