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	$162.33	7.169%	$173.9674	$173.97	$173.95	$174.00
Purchase #2	$164.79	11.258%	$183.3421	$183.34	$183.35	$183.30
Purchase #3	$59.39	13.187%	$67.2218	$67.22	$67.20	$67.20
Purchase #4	$206.48	8.420%	$223.8656	$223.87	$223.85	$223.90
Purchase #5	$151.36	10.142%	$166.7109	$166.71	$166.70	$166.70
Purchase #6	$33.52	13.309%	$37.9812	$37.98	$38.00	$38.00
Purchase #7	$154.28	6.119%	$163.7204	$163.72	$163.70	$163.70
7 purchase totals =	$932.15		$1,016.8094	$1,016.81	$1,016.75	$1,016.80