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	$182.97	7.596%	$196.8684	$196.87	$196.85	$196.90
Purchase #2	$94.27	13.279%	$106.7881	$106.79	$106.80	$106.80
Purchase #3	$82.93	7.369%	$89.0411	$89.04	$89.05	$89.00
Purchase #4	$21.95	9.112%	$23.9501	$23.95	$23.95	$24.00
Purchase #5	$150.34	10.541%	$166.1873	$166.19	$166.20	$166.20
Purchase #6	$142.61	10.381%	$157.4143	$157.41	$157.40	$157.40
Purchase #7	$88.50	6.418%	$94.1799	$94.18	$94.20	$94.20
7 purchase totals =	$763.57		$834.4292	$834.43	$834.45	$834.50