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	$195.57	7.556%	$210.3473	$210.35	$210.35	$210.30
Purchase #2	$41.69	4.599%	$43.6073	$43.61	$43.60	$43.60
Purchase #3	$173.95	8.123%	$188.08	$188.08	$188.10	$188.10
Purchase #4	$135.89	13.672%	$154.4689	$154.47	$154.45	$154.50
Purchase #5	$93.91	8.147%	$101.5608	$101.56	$101.55	$101.60
Purchase #6	$59.34	10.303%	$65.4538	$65.45	$65.45	$65.50
Purchase #7	$24.90	3.842%	$25.8567	$25.86	$25.85	$25.90
7 purchase totals =	$725.25		$789.3748	$789.38	$789.35	$789.50