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	$82.46	3.743%	$85.5465	$85.55	$85.55	$85.50
Purchase #2	$203.61	6.371%	$216.582	$216.58	$216.60	$216.60
Purchase #3	$140.28	4.544%	$146.6543	$146.65	$146.65	$146.70
Purchase #4	$231.33	5.344%	$243.6923	$243.69	$243.70	$243.70
Purchase #5	$118.50	6.135%	$125.77	$125.77	$125.75	$125.80
Purchase #6	$62.86	13.741%	$71.4976	$71.50	$71.50	$71.50
Purchase #7	$112.35	6.188%	$119.3022	$119.30	$119.30	$119.30
7 purchase totals =	$951.39		$1,009.0449	$1,009.04	$1,009.05	$1,009.10