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	$151.71	7.359%	$162.8743	$162.87	$162.85	$162.90
Purchase #2	$85.33	6.109%	$90.5428	$90.54	$90.55	$90.50
Purchase #3	$129.55	4.773%	$135.7334	$135.73	$135.75	$135.70
Purchase #4	$32.59	10.850%	$36.126	$36.13	$36.15	$36.10
Purchase #5	$137.88	7.669%	$148.454	$148.45	$148.45	$148.50
Purchase #6	$222.74	6.636%	$237.521	$237.52	$237.50	$237.50
Purchase #7	$174.62	11.317%	$194.3817	$194.38	$194.40	$194.40
7 purchase totals =	$934.42		$1,005.6332	$1,005.62	$1,005.65	$1,005.60