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	$152.86	10.156%	$168.3845	$168.38	$168.40	$168.40
Purchase #2	$55.67	7.566%	$59.882	$59.88	$59.90	$59.90
Purchase #3	$95.50	9.348%	$104.4273	$104.43	$104.45	$104.40
Purchase #4	$34.73	12.362%	$39.0233	$39.02	$39.00	$39.00
Purchase #5	$211.94	9.102%	$231.2308	$231.23	$231.25	$231.20
Purchase #6	$233.26	4.286%	$243.2575	$243.26	$243.25	$243.30
Purchase #7	$201.86	7.469%	$216.9369	$216.94	$216.95	$216.90
7 purchase totals =	$985.82		$1,063.1423	$1,063.14	$1,063.20	$1,063.10