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	$195.35	8.319%	$211.6012	$211.60	$211.60	$211.60
Purchase #2	$207.97	12.203%	$233.3486	$233.35	$233.35	$233.30
Purchase #3	$93.54	12.873%	$105.5814	$105.58	$105.60	$105.60
Purchase #4	$227.86	9.690%	$249.9396	$249.94	$249.95	$249.90
Purchase #5	$69.41	12.459%	$78.0578	$78.06	$78.05	$78.10
Purchase #6	$63.40	5.752%	$67.0468	$67.05	$67.05	$67.00
Purchase #7	$96.68	4.367%	$100.902	$100.90	$100.90	$100.90
7 purchase totals =	$954.21		$1,046.4774	$1,046.48	$1,046.50	$1,046.40