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	$186.25	4.641%	$194.8939	$194.89	$194.90	$194.90
Purchase #2	$155.86	9.567%	$170.7711	$170.77	$170.75	$170.80
Purchase #3	$95.71	9.712%	$105.0054	$105.01	$105.00	$105.00
Purchase #4	$183.32	6.587%	$195.3953	$195.40	$195.40	$195.40
Purchase #5	$190.62	3.254%	$196.8228	$196.82	$196.80	$196.80
Purchase #6	$143.72	9.552%	$157.4481	$157.45	$157.45	$157.40
Purchase #7	$216.37	12.553%	$243.5309	$243.53	$243.55	$243.50
7 purchase totals =	$1,171.85		$1,263.8675	$1,263.87	$1,263.85	$1,263.80