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	$240.94	8.212%	$260.726	$260.73	$260.75	$260.70
Purchase #2	$199.82	5.693%	$211.1958	$211.20	$211.20	$211.20
Purchase #3	$54.27	11.304%	$60.4047	$60.40	$60.40	$60.40
Purchase #4	$224.73	6.245%	$238.7644	$238.76	$238.75	$238.80
Purchase #5	$209.53	6.297%	$222.7241	$222.72	$222.70	$222.70
Purchase #6	$42.27	3.822%	$43.8856	$43.89	$43.90	$43.90
Purchase #7	$93.73	12.576%	$105.5175	$105.52	$105.50	$105.50
7 purchase totals =	$1,065.29		$1,143.2181	$1,143.22	$1,143.20	$1,143.20