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	$182.47	7.145%	$195.5075	$195.51	$195.50	$195.50
Purchase #2	$66.93	6.572%	$71.3286	$71.33	$71.35	$71.30
Purchase #3	$142.85	5.512%	$150.7239	$150.72	$150.70	$150.70
Purchase #4	$141.83	5.672%	$149.8746	$149.87	$149.85	$149.90
Purchase #5	$60.33	10.248%	$66.5126	$66.51	$66.50	$66.50
Purchase #6	$14.31	10.429%	$15.8024	$15.80	$15.80	$15.80
Purchase #7	$180.53	10.561%	$199.5958	$199.60	$199.60	$199.60
7 purchase totals =	$789.25		$849.3454	$849.34	$849.30	$849.30