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	$175.62	7.319%	$188.4736	$188.47	$188.45	$188.50
Purchase #2	$24.37	5.511%	$25.713	$25.71	$25.70	$25.70
Purchase #3	$183.27	3.339%	$189.3894	$189.39	$189.40	$189.40
Purchase #4	$78.83	13.595%	$89.5469	$89.55	$89.55	$89.50
Purchase #5	$52.40	13.338%	$59.3891	$59.39	$59.40	$59.40
Purchase #6	$78.97	4.216%	$82.2994	$82.30	$82.30	$82.30
Purchase #7	$216.40	8.222%	$234.1924	$234.19	$234.20	$234.20
7 purchase totals =	$809.86		$869.0038	$869.00	$869.00	$869.00