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	$168.82	4.223%	$175.9493	$175.95	$175.95	$175.90
Purchase #2	$168.85	6.661%	$180.0971	$180.10	$180.10	$180.10
Purchase #3	$99.62	4.823%	$104.4247	$104.42	$104.40	$104.40
Purchase #4	$232.69	13.654%	$264.4615	$264.46	$264.45	$264.50
Purchase #5	$38.72	8.581%	$42.0426	$42.04	$42.05	$42.00
Purchase #6	$175.91	11.788%	$196.6463	$196.65	$196.65	$196.60
Purchase #7	$234.35	7.310%	$251.481	$251.48	$251.50	$251.50
7 purchase totals =	$1,118.96		$1,215.1025	$1,215.10	$1,215.10	$1,215.00