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	$67.31	10.548%	$74.4099	$74.41	$74.40	$74.40
Purchase #2	$90.32	6.207%	$95.9262	$95.93	$95.95	$95.90
Purchase #3	$5.80	6.132%	$6.1557	$6.16	$6.15	$6.20
Purchase #4	$40.90	3.857%	$42.4775	$42.48	$42.50	$42.50
Purchase #5	$172.58	13.664%	$196.1613	$196.16	$196.15	$196.20
Purchase #6	$170.82	13.641%	$194.1216	$194.12	$194.10	$194.10
Purchase #7	$13.49	7.473%	$14.4981	$14.50	$14.50	$14.50
7 purchase totals =	$561.22		$623.7503	$623.76	$623.75	$623.80