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	$211.82	3.737%	$219.7357	$219.74	$219.75	$219.70
Purchase #2	$118.91	8.419%	$128.921	$128.92	$128.90	$128.90
Purchase #3	$213.83	7.144%	$229.106	$229.11	$229.10	$229.10
Purchase #4	$151.93	8.522%	$164.8775	$164.88	$164.90	$164.90
Purchase #5	$67.87	10.524%	$75.0126	$75.01	$75.00	$75.00
Purchase #6	$38.44	4.113%	$40.021	$40.02	$40.00	$40.00
Purchase #7	$145.42	9.181%	$158.771	$158.77	$158.75	$158.80
7 purchase totals =	$948.22		$1,016.4448	$1,016.45	$1,016.40	$1,016.40