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	$195.98	6.315%	$208.3561	$208.36	$208.35	$208.40
Purchase #2	$235.78	12.424%	$265.0733	$265.07	$265.05	$265.10
Purchase #3	$40.79	11.185%	$45.3524	$45.35	$45.35	$45.40
Purchase #4	$151.83	5.556%	$160.2657	$160.27	$160.25	$160.30
Purchase #5	$95.30	9.180%	$104.0485	$104.05	$104.05	$104.00
Purchase #6	$182.35	7.539%	$196.0974	$196.10	$196.10	$196.10
Purchase #7	$49.33	12.249%	$55.3724	$55.37	$55.35	$55.40
7 purchase totals =	$951.36		$1,034.5658	$1,034.57	$1,034.50	$1,034.70