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	$133.66	11.124%	$148.5283	$148.53	$148.55	$148.50
Purchase #2	$10.55	6.783%	$11.2656	$11.27	$11.25	$11.30
Purchase #3	$200.53	10.323%	$221.2307	$221.23	$221.25	$221.20
Purchase #4	$143.43	3.698%	$148.734	$148.73	$148.75	$148.70
Purchase #5	$59.41	13.820%	$67.6205	$67.62	$67.60	$67.60
Purchase #6	$194.77	8.396%	$211.1229	$211.12	$211.10	$211.10
Purchase #7	$213.37	6.649%	$227.557	$227.56	$227.55	$227.60
7 purchase totals =	$955.72		$1,036.0590	$1,036.06	$1,036.05	$1,036.00