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	$61.76	9.516%	$67.6371	$67.64	$67.65	$67.60
Purchase #2	$77.82	6.312%	$82.732	$82.73	$82.75	$82.70
Purchase #3	$36.93	3.345%	$38.1653	$38.17	$38.15	$38.20
Purchase #4	$220.86	4.866%	$231.607	$231.61	$231.60	$231.60
Purchase #5	$221.47	8.263%	$239.7701	$239.77	$239.75	$239.80
Purchase #6	$127.87	4.193%	$133.2316	$133.23	$133.25	$133.20
Purchase #7	$192.98	12.849%	$217.776	$217.78	$217.80	$217.80
7 purchase totals =	$939.69		$1,010.9191	$1,010.93	$1,010.95	$1,010.90