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	$86.72	8.367%	$93.9759	$93.98	$94.00	$94.00
Purchase #2	$95.76	10.173%	$105.5017	$105.50	$105.50	$105.50
Purchase #3	$199.76	11.626%	$222.9841	$222.98	$223.00	$223.00
Purchase #4	$6.37	13.766%	$7.2469	$7.25	$7.25	$7.20
Purchase #5	$64.62	10.692%	$71.5292	$71.53	$71.55	$71.50
Purchase #6	$115.93	9.818%	$127.312	$127.31	$127.30	$127.30
Purchase #7	$66.46	11.407%	$74.0411	$74.04	$74.05	$74.00
7 purchase totals =	$635.62		$702.5909	$702.59	$702.65	$702.50