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	$181.50	8.351%	$196.6571	$196.66	$196.65	$196.70
Purchase #2	$92.97	8.395%	$100.7748	$100.77	$100.75	$100.80
Purchase #3	$153.76	7.627%	$165.4873	$165.49	$165.50	$165.50
Purchase #4	$161.27	7.752%	$173.7717	$173.77	$173.75	$173.80
Purchase #5	$55.31	8.112%	$59.7967	$59.80	$59.80	$59.80
Purchase #6	$203.79	7.862%	$219.812	$219.81	$219.80	$219.80
Purchase #7	$43.68	3.145%	$45.0537	$45.05	$45.05	$45.10
7 purchase totals =	$892.28		$961.3533	$961.35	$961.30	$961.50