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	$32.45	4.452%	$33.8947	$33.89	$33.90	$33.90
Purchase #2	$7.30	4.571%	$7.6337	$7.63	$7.65	$7.60
Purchase #3	$213.41	4.727%	$223.4979	$223.50	$223.50	$223.50
Purchase #4	$208.53	8.168%	$225.5627	$225.56	$225.55	$225.60
Purchase #5	$85.83	9.842%	$94.2774	$94.28	$94.30	$94.30
Purchase #6	$90.61	5.797%	$95.8627	$95.86	$95.85	$95.90
Purchase #7	$95.61	9.841%	$105.019	$105.02	$105.00	$105.00
7 purchase totals =	$733.74		$785.7481	$785.74	$785.75	$785.80