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	$88.35	7.487%	$94.9648	$94.96	$94.95	$95.00
Purchase #2	$64.43	10.604%	$71.2622	$71.26	$71.25	$71.30
Purchase #3	$249.90	13.133%	$282.7194	$282.72	$282.70	$282.70
Purchase #4	$168.37	13.651%	$191.3542	$191.35	$191.35	$191.40
Purchase #5	$237.30	3.358%	$245.2685	$245.27	$245.25	$245.30
Purchase #6	$216.35	7.766%	$233.1517	$233.15	$233.15	$233.20
Purchase #7	$11.50	12.679%	$12.9581	$12.96	$12.95	$13.00
7 purchase totals =	$1,036.20		$1,131.6789	$1,131.67	$1,131.60	$1,131.90