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	$186.64	5.518%	$196.9388	$196.94	$196.95	$196.90
Purchase #2	$26.61	12.220%	$29.8617	$29.86	$29.85	$29.90
Purchase #3	$122.53	4.498%	$128.0414	$128.04	$128.05	$128.00
Purchase #4	$161.78	11.180%	$179.867	$179.87	$179.85	$179.90
Purchase #5	$239.79	6.710%	$255.8799	$255.88	$255.90	$255.90
Purchase #6	$194.64	13.613%	$221.1363	$221.14	$221.15	$221.10
Purchase #7	$40.66	10.512%	$44.9342	$44.93	$44.95	$44.90
7 purchase totals =	$972.65		$1,056.6593	$1,056.66	$1,056.70	$1,056.60