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	$172.64	13.665%	$196.2313	$196.23	$196.25	$196.20
Purchase #2	$119.99	11.147%	$133.3653	$133.37	$133.35	$133.40
Purchase #3	$85.81	12.692%	$96.701	$96.70	$96.70	$96.70
Purchase #4	$208.61	7.248%	$223.7301	$223.73	$223.75	$223.70
Purchase #5	$96.63	11.802%	$108.0343	$108.03	$108.05	$108.00
Purchase #6	$154.59	4.162%	$161.024	$161.02	$161.00	$161.00
Purchase #7	$170.96	8.140%	$184.8761	$184.88	$184.90	$184.90
7 purchase totals =	$1,009.23		$1,103.9621	$1,103.96	$1,104.00	$1,103.90