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	$213.68	10.314%	$235.719	$235.72	$235.70	$235.70
Purchase #2	$38.62	10.663%	$42.7381	$42.74	$42.75	$42.70
Purchase #3	$64.79	10.338%	$71.488	$71.49	$71.50	$71.50
Purchase #4	$214.37	9.744%	$235.2582	$235.26	$235.25	$235.30
Purchase #5	$43.51	4.631%	$45.5249	$45.52	$45.50	$45.50
Purchase #6	$202.48	8.414%	$219.5167	$219.52	$219.50	$219.50
Purchase #7	$137.77	13.698%	$156.6417	$156.64	$156.65	$156.60
7 purchase totals =	$915.22		$1,006.8866	$1,006.89	$1,006.85	$1,006.80