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	$216.75	7.712%	$233.4658	$233.47	$233.45	$233.50
Purchase #2	$34.29	3.484%	$35.4847	$35.48	$35.50	$35.50
Purchase #3	$129.98	13.746%	$147.8471	$147.85	$147.85	$147.80
Purchase #4	$176.56	11.120%	$196.1935	$196.19	$196.20	$196.20
Purchase #5	$65.83	9.272%	$71.9338	$71.93	$71.95	$71.90
Purchase #6	$129.41	3.123%	$133.4515	$133.45	$133.45	$133.50
Purchase #7	$60.92	5.357%	$64.1835	$64.18	$64.20	$64.20
7 purchase totals =	$813.74		$882.5599	$882.55	$882.60	$882.60