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	$175.50	11.220%	$195.1911	$195.19	$195.20	$195.20
Purchase #2	$69.38	4.617%	$72.5833	$72.58	$72.60	$72.60
Purchase #3	$117.74	4.640%	$123.2031	$123.20	$123.20	$123.20
Purchase #4	$76.93	8.569%	$83.5221	$83.52	$83.50	$83.50
Purchase #5	$67.71	7.106%	$72.5215	$72.52	$72.50	$72.50
Purchase #6	$118.82	8.367%	$128.7617	$128.76	$128.75	$128.80
Purchase #7	$196.97	12.365%	$221.3253	$221.33	$221.35	$221.30
7 purchase totals =	$823.05		$897.1081	$897.10	$897.10	$897.10