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	$192.76	13.856%	$219.4688	$219.47	$219.45	$219.50
Purchase #2	$97.81	13.394%	$110.9107	$110.91	$110.90	$110.90
Purchase #3	$93.88	12.317%	$105.4432	$105.44	$105.45	$105.40
Purchase #4	$129.31	11.264%	$143.8755	$143.88	$143.90	$143.90
Purchase #5	$73.89	11.636%	$82.4878	$82.49	$82.50	$82.50
Purchase #6	$191.90	8.162%	$207.5629	$207.56	$207.55	$207.60
Purchase #7	$203.84	5.110%	$214.2562	$214.26	$214.25	$214.30
7 purchase totals =	$983.39		$1,084.0051	$1,084.01	$1,084.00	$1,084.10