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	$195.92	13.806%	$222.9687	$222.97	$222.95	$223.00
Purchase #2	$76.90	11.128%	$85.4574	$85.46	$85.45	$85.50
Purchase #3	$32.84	8.377%	$35.591	$35.59	$35.60	$35.60
Purchase #4	$234.74	9.151%	$256.2211	$256.22	$256.20	$256.20
Purchase #5	$47.96	9.104%	$52.3263	$52.33	$52.35	$52.30
Purchase #6	$118.57	4.458%	$123.8559	$123.86	$123.85	$123.90
Purchase #7	$215.40	8.512%	$233.7348	$233.73	$233.75	$233.70
7 purchase totals =	$922.33		$1,010.1552	$1,010.16	$1,010.15	$1,010.20