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	$119.46	3.406%	$123.5288	$123.53	$123.55	$123.50
Purchase #2	$11.40	6.603%	$12.1527	$12.15	$12.15	$12.20
Purchase #3	$168.33	9.639%	$184.5553	$184.56	$184.55	$184.60
Purchase #4	$216.32	3.169%	$223.1752	$223.18	$223.20	$223.20
Purchase #5	$39.78	7.836%	$42.8972	$42.90	$42.90	$42.90
Purchase #6	$152.47	4.158%	$158.8097	$158.81	$158.80	$158.80
Purchase #7	$204.28	6.705%	$217.977	$217.98	$218.00	$218.00
7 purchase totals =	$912.04		$963.0959	$963.11	$963.15	$963.20