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	$213.73	4.225%	$222.7601	$222.76	$222.75	$222.80
Purchase #2	$224.32	12.841%	$253.1249	$253.12	$253.10	$253.10
Purchase #3	$194.41	7.454%	$208.9013	$208.90	$208.90	$208.90
Purchase #4	$155.70	10.508%	$172.061	$172.06	$172.05	$172.10
Purchase #5	$140.62	3.696%	$145.8173	$145.82	$145.80	$145.80
Purchase #6	$18.85	3.695%	$19.5465	$19.55	$19.55	$19.50
Purchase #7	$56.25	5.294%	$59.2279	$59.23	$59.25	$59.20
7 purchase totals =	$1,003.88		$1,081.4390	$1,081.44	$1,081.40	$1,081.40