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	$73.61	3.660%	$76.3041	$76.30	$76.30	$76.30
Purchase #2	$226.28	3.852%	$234.9963	$235.00	$235.00	$235.00
Purchase #3	$74.90	10.191%	$82.5331	$82.53	$82.55	$82.50
Purchase #4	$83.64	8.402%	$90.6674	$90.67	$90.65	$90.70
Purchase #5	$249.57	5.150%	$262.4229	$262.42	$262.40	$262.40
Purchase #6	$39.90	8.772%	$43.4	$43.40	$43.40	$43.40
Purchase #7	$226.56	6.770%	$241.8981	$241.90	$241.90	$241.90
7 purchase totals =	$974.46		$1,032.2219	$1,032.22	$1,032.20	$1,032.20