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	$140.32	9.566%	$153.743	$153.74	$153.75	$153.70
Purchase #2	$11.46	3.351%	$11.844	$11.84	$11.85	$11.80
Purchase #3	$246.53	3.540%	$255.2572	$255.26	$255.25	$255.30
Purchase #4	$246.74	6.760%	$263.4196	$263.42	$263.40	$263.40
Purchase #5	$98.84	12.790%	$111.4816	$111.48	$111.50	$111.50
Purchase #6	$94.56	9.815%	$103.8411	$103.84	$103.85	$103.80
Purchase #7	$218.87	6.584%	$233.2804	$233.28	$233.30	$233.30
7 purchase totals =	$1,057.32		$1,132.8669	$1,132.86	$1,132.90	$1,132.80