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	$216.39	8.134%	$233.9912	$233.99	$234.00	$234.00
Purchase #2	$6.92	5.476%	$7.2989	$7.30	$7.30	$7.30
Purchase #3	$76.38	9.784%	$83.853	$83.85	$83.85	$83.90
Purchase #4	$179.67	4.472%	$187.7048	$187.70	$187.70	$187.70
Purchase #5	$189.56	9.821%	$208.1767	$208.18	$208.20	$208.20
Purchase #6	$65.49	9.309%	$71.5865	$71.59	$71.60	$71.60
Purchase #7	$98.30	13.600%	$111.6688	$111.67	$111.65	$111.70
7 purchase totals =	$832.71		$904.2799	$904.28	$904.30	$904.40