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	$32.83	6.756%	$35.048	$35.05	$35.05	$35.00
Purchase #2	$29.52	7.302%	$31.6756	$31.68	$31.70	$31.70
Purchase #3	$211.51	7.334%	$227.0221	$227.02	$227.00	$227.00
Purchase #4	$105.38	5.655%	$111.3392	$111.34	$111.35	$111.30
Purchase #5	$219.84	6.278%	$233.6416	$233.64	$233.65	$233.60
Purchase #6	$185.65	12.178%	$208.2585	$208.26	$208.25	$208.30
Purchase #7	$185.30	12.713%	$208.8572	$208.86	$208.85	$208.90
7 purchase totals =	$970.03		$1,055.8422	$1,055.85	$1,055.85	$1,055.80