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	$118.63	5.325%	$124.947	$124.95	$124.95	$124.90
Purchase #2	$84.40	6.754%	$90.1004	$90.10	$90.10	$90.10
Purchase #3	$223.52	7.402%	$240.065	$240.07	$240.05	$240.10
Purchase #4	$162.73	5.813%	$172.1895	$172.19	$172.20	$172.20
Purchase #5	$75.63	13.543%	$85.8726	$85.87	$85.85	$85.90
Purchase #6	$78.94	12.752%	$89.0064	$89.01	$89.00	$89.00
Purchase #7	$148.40	12.321%	$166.6844	$166.68	$166.70	$166.70
7 purchase totals =	$892.25		$968.8653	$968.87	$968.85	$968.90