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	$142.39	5.858%	$150.7312	$150.73	$150.75	$150.70
Purchase #2	$89.90	9.140%	$98.1169	$98.12	$98.10	$98.10
Purchase #3	$13.73	5.628%	$14.5027	$14.50	$14.50	$14.50
Purchase #4	$48.77	6.404%	$51.8932	$51.89	$51.90	$51.90
Purchase #5	$91.62	4.227%	$95.4928	$95.49	$95.50	$95.50
Purchase #6	$42.58	11.637%	$47.535	$47.54	$47.55	$47.50
Purchase #7	$232.31	4.744%	$243.3308	$243.33	$243.35	$243.30
7 purchase totals =	$661.30		$701.6026	$701.60	$701.65	$701.50