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	$208.37	3.110%	$214.8503	$214.85	$214.85	$214.90
Purchase #2	$197.83	12.307%	$222.1769	$222.18	$222.20	$222.20
Purchase #3	$166.54	11.725%	$186.0668	$186.07	$186.05	$186.10
Purchase #4	$30.81	7.124%	$33.0049	$33.00	$33.00	$33.00
Purchase #5	$89.59	6.541%	$95.4501	$95.45	$95.45	$95.50
Purchase #6	$98.35	11.421%	$109.5826	$109.58	$109.60	$109.60
Purchase #7	$247.33	6.614%	$263.6884	$263.69	$263.70	$263.70
7 purchase totals =	$1,038.82		$1,124.8200	$1,124.82	$1,124.85	$1,125.00