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	$196.99	9.353%	$215.4145	$215.41	$215.40	$215.40
Purchase #2	$74.58	5.871%	$78.9586	$78.96	$78.95	$79.00
Purchase #3	$218.81	5.304%	$230.4157	$230.42	$230.40	$230.40
Purchase #4	$136.78	8.343%	$148.1916	$148.19	$148.20	$148.20
Purchase #5	$169.98	11.835%	$190.0971	$190.10	$190.10	$190.10
Purchase #6	$211.28	5.401%	$222.6912	$222.69	$222.70	$222.70
Purchase #7	$94.32	5.545%	$99.55	$99.55	$99.55	$99.60
7 purchase totals =	$1,102.74		$1,185.3187	$1,185.32	$1,185.30	$1,185.40