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	$200.27	11.795%	$223.8918	$223.89	$223.90	$223.90
Purchase #2	$85.42	11.755%	$95.4611	$95.46	$95.45	$95.50
Purchase #3	$196.78	3.814%	$204.2852	$204.29	$204.30	$204.30
Purchase #4	$172.60	11.663%	$192.7303	$192.73	$192.75	$192.70
Purchase #5	$190.34	12.358%	$213.8622	$213.86	$213.85	$213.90
Purchase #6	$162.33	11.833%	$181.5385	$181.54	$181.55	$181.50
Purchase #7	$56.96	6.685%	$60.7678	$60.77	$60.75	$60.80
7 purchase totals =	$1,064.70		$1,172.5369	$1,172.54	$1,172.55	$1,172.60