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	$153.93	5.798%	$162.8549	$162.85	$162.85	$162.90
Purchase #2	$125.29	4.674%	$131.1461	$131.15	$131.15	$131.10
Purchase #3	$69.46	12.284%	$77.9925	$77.99	$78.00	$78.00
Purchase #4	$231.78	4.141%	$241.378	$241.38	$241.40	$241.40
Purchase #5	$180.48	5.594%	$190.5761	$190.58	$190.60	$190.60
Purchase #6	$175.84	13.117%	$198.9049	$198.90	$198.90	$198.90
Purchase #7	$178.33	10.220%	$196.5553	$196.56	$196.55	$196.60
7 purchase totals =	$1,115.11		$1,199.4078	$1,199.41	$1,199.45	$1,199.50