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	$71.41	9.165%	$77.9547	$77.95	$77.95	$78.00
Purchase #2	$100.38	13.185%	$113.6151	$113.62	$113.60	$113.60
Purchase #3	$226.93	6.388%	$241.4263	$241.43	$241.45	$241.40
Purchase #4	$248.79	11.314%	$276.9381	$276.94	$276.95	$276.90
Purchase #5	$148.97	3.799%	$154.6294	$154.63	$154.65	$154.60
Purchase #6	$243.57	11.278%	$271.0398	$271.04	$271.05	$271.00
Purchase #7	$55.26	10.439%	$61.0286	$61.03	$61.05	$61.00
7 purchase totals =	$1,095.31		$1,196.6320	$1,196.64	$1,196.70	$1,196.50