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	$196.33	10.862%	$217.6554	$217.66	$217.65	$217.70
Purchase #2	$207.99	7.154%	$222.8696	$222.87	$222.85	$222.90
Purchase #3	$95.51	8.427%	$103.5586	$103.56	$103.55	$103.60
Purchase #4	$196.69	13.664%	$223.5657	$223.57	$223.55	$223.60
Purchase #5	$63.62	13.137%	$71.9778	$71.98	$72.00	$72.00
Purchase #6	$109.67	3.470%	$113.4755	$113.48	$113.50	$113.50
Purchase #7	$53.47	11.713%	$59.7329	$59.73	$59.75	$59.70
7 purchase totals =	$923.28		$1,012.8355	$1,012.85	$1,012.85	$1,013.00