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	$95.40	6.844%	$101.9292	$101.93	$101.95	$101.90
Purchase #2	$41.79	10.195%	$46.0505	$46.05	$46.05	$46.10
Purchase #3	$69.25	5.256%	$72.8898	$72.89	$72.90	$72.90
Purchase #4	$34.52	4.811%	$36.1808	$36.18	$36.20	$36.20
Purchase #5	$46.27	9.744%	$50.7785	$50.78	$50.80	$50.80
Purchase #6	$242.92	12.853%	$274.1425	$274.14	$274.15	$274.10
Purchase #7	$86.37	11.218%	$96.059	$96.06	$96.05	$96.10
7 purchase totals =	$616.52		$678.0303	$678.03	$678.10	$678.10