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	$191.86	3.818%	$199.1852	$199.19	$199.20	$199.20
Purchase #2	$199.82	4.718%	$209.2475	$209.25	$209.25	$209.20
Purchase #3	$10.98	3.642%	$11.3799	$11.38	$11.40	$11.40
Purchase #4	$81.71	10.178%	$90.0264	$90.03	$90.05	$90.00
Purchase #5	$214.32	4.797%	$224.6009	$224.60	$224.60	$224.60
Purchase #6	$245.98	3.760%	$255.2288	$255.23	$255.25	$255.20
Purchase #7	$59.41	12.747%	$66.983	$66.98	$67.00	$67.00
7 purchase totals =	$1,004.08		$1,056.6517	$1,056.66	$1,056.75	$1,056.60