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	$210.41	7.368%	$225.913	$225.91	$225.90	$225.90
Purchase #2	$68.94	4.529%	$72.0623	$72.06	$72.05	$72.10
Purchase #3	$117.77	4.499%	$123.0685	$123.07	$123.05	$123.10
Purchase #4	$112.55	12.714%	$126.8596	$126.86	$126.85	$126.90
Purchase #5	$81.27	13.725%	$92.4243	$92.42	$92.40	$92.40
Purchase #6	$45.53	3.143%	$46.961	$46.96	$46.95	$47.00
Purchase #7	$101.32	10.377%	$111.834	$111.83	$111.85	$111.80
7 purchase totals =	$737.79		$799.1227	$799.11	$799.05	$799.20