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	$59.65	9.494%	$65.3132	$65.31	$65.30	$65.30
Purchase #2	$87.55	9.516%	$95.8813	$95.88	$95.90	$95.90
Purchase #3	$111.63	6.606%	$119.0043	$119.00	$119.00	$119.00
Purchase #4	$43.73	10.148%	$48.1677	$48.17	$48.15	$48.20
Purchase #5	$58.73	11.143%	$65.2743	$65.27	$65.25	$65.30
Purchase #6	$6.54	9.503%	$7.1615	$7.16	$7.15	$7.20
Purchase #7	$38.91	7.154%	$41.6936	$41.69	$41.70	$41.70
7 purchase totals =	$406.74		$442.4959	$442.48	$442.45	$442.60