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	$176.57	10.869%	$195.7614	$195.76	$195.75	$195.80
Purchase #2	$133.87	13.318%	$151.6988	$151.70	$151.70	$151.70
Purchase #3	$70.30	3.340%	$72.648	$72.65	$72.65	$72.60
Purchase #4	$187.47	6.588%	$199.8205	$199.82	$199.80	$199.80
Purchase #5	$187.96	6.158%	$199.5346	$199.53	$199.55	$199.50
Purchase #6	$127.96	11.698%	$142.9288	$142.93	$142.95	$142.90
Purchase #7	$39.46	10.150%	$43.4652	$43.47	$43.45	$43.50
7 purchase totals =	$923.59		$1,005.8573	$1,005.86	$1,005.85	$1,005.80