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	$187.94	3.854%	$195.1832	$195.18	$195.20	$195.20
Purchase #2	$24.34	3.363%	$25.1586	$25.16	$25.15	$25.20
Purchase #3	$54.67	8.788%	$59.4744	$59.47	$59.45	$59.50
Purchase #4	$56.59	11.663%	$63.1901	$63.19	$63.20	$63.20
Purchase #5	$94.75	4.820%	$99.317	$99.32	$99.30	$99.30
Purchase #6	$109.83	9.815%	$120.6098	$120.61	$120.60	$120.60
Purchase #7	$196.77	13.384%	$223.1057	$223.11	$223.10	$223.10
7 purchase totals =	$724.89		$786.0388	$786.04	$786.00	$786.10