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	$200.73	4.153%	$209.0663	$209.07	$209.05	$209.10
Purchase #2	$202.59	7.629%	$218.0456	$218.05	$218.05	$218.00
Purchase #3	$37.74	5.161%	$39.6878	$39.69	$39.70	$39.70
Purchase #4	$68.35	6.468%	$72.7709	$72.77	$72.75	$72.80
Purchase #5	$130.45	9.145%	$142.3797	$142.38	$142.40	$142.40
Purchase #6	$220.68	5.696%	$233.2499	$233.25	$233.25	$233.20
Purchase #7	$162.41	11.258%	$180.6941	$180.69	$180.70	$180.70
7 purchase totals =	$1,022.95		$1,095.8943	$1,095.90	$1,095.90	$1,095.90