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	$146.48	6.232%	$155.6086	$155.61	$155.60	$155.60
Purchase #2	$110.91	11.229%	$123.3641	$123.36	$123.35	$123.40
Purchase #3	$36.80	7.736%	$39.6468	$39.65	$39.65	$39.60
Purchase #4	$187.59	4.723%	$196.4499	$196.45	$196.45	$196.40
Purchase #5	$151.41	8.621%	$164.4631	$164.46	$164.45	$164.50
Purchase #6	$164.93	6.354%	$175.4097	$175.41	$175.40	$175.40
Purchase #7	$157.33	7.422%	$169.007	$169.01	$169.00	$169.00
7 purchase totals =	$955.45		$1,023.9492	$1,023.95	$1,023.90	$1,023.90