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	$92.78	4.128%	$96.61	$96.61	$96.60	$96.60
Purchase #2	$41.97	3.530%	$43.4515	$43.45	$43.45	$43.50
Purchase #3	$48.66	12.190%	$54.5917	$54.59	$54.60	$54.60
Purchase #4	$66.33	4.645%	$69.411	$69.41	$69.40	$69.40
Purchase #5	$47.47	8.110%	$51.3198	$51.32	$51.30	$51.30
Purchase #6	$7.59	12.788%	$8.5606	$8.56	$8.55	$8.60
Purchase #7	$74.35	12.235%	$83.4467	$83.45	$83.45	$83.40
7 purchase totals =	$379.15		$407.3913	$407.39	$407.35	$407.40