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	$79.46	10.400%	$87.7238	$87.72	$87.70	$87.70
Purchase #2	$188.47	4.117%	$196.2293	$196.23	$196.25	$196.20
Purchase #3	$172.88	4.172%	$180.0926	$180.09	$180.10	$180.10
Purchase #4	$11.36	4.661%	$11.8895	$11.89	$11.90	$11.90
Purchase #5	$145.78	7.860%	$157.2383	$157.24	$157.25	$157.20
Purchase #6	$185.36	11.201%	$206.1222	$206.12	$206.10	$206.10
Purchase #7	$167.76	5.433%	$176.8744	$176.87	$176.85	$176.90
7 purchase totals =	$951.07		$1,016.1701	$1,016.16	$1,016.15	$1,016.10