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	$56.48	10.292%	$62.2929	$62.29	$62.30	$62.30
Purchase #2	$130.32	4.615%	$136.3343	$136.33	$136.35	$136.30
Purchase #3	$148.50	4.868%	$155.729	$155.73	$155.75	$155.70
Purchase #4	$178.62	6.663%	$190.5215	$190.52	$190.50	$190.50
Purchase #5	$76.28	6.347%	$81.1215	$81.12	$81.10	$81.10
Purchase #6	$114.56	11.387%	$127.6049	$127.60	$127.60	$127.60
Purchase #7	$203.90	3.859%	$211.7685	$211.77	$211.75	$211.80
7 purchase totals =	$908.66		$965.3726	$965.36	$965.35	$965.30