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	$212.38	7.679%	$228.6887	$228.69	$228.70	$228.70
Purchase #2	$243.56	7.745%	$262.4237	$262.42	$262.40	$262.40
Purchase #3	$30.58	7.281%	$32.8065	$32.81	$32.80	$32.80
Purchase #4	$132.29	9.593%	$144.9806	$144.98	$145.00	$145.00
Purchase #5	$152.53	5.851%	$161.4545	$161.45	$161.45	$161.50
Purchase #6	$127.89	6.600%	$136.3307	$136.33	$136.35	$136.30
Purchase #7	$32.98	8.659%	$35.8357	$35.84	$35.85	$35.80
7 purchase totals =	$932.21		$1,002.5204	$1,002.52	$1,002.55	$1,002.50