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	$233.25	5.323%	$245.6659	$245.67	$245.65	$245.70
Purchase #2	$88.43	11.432%	$98.5393	$98.54	$98.55	$98.50
Purchase #3	$151.36	9.362%	$165.5303	$165.53	$165.55	$165.50
Purchase #4	$98.86	6.300%	$105.0882	$105.09	$105.10	$105.10
Purchase #5	$122.34	13.578%	$138.9513	$138.95	$138.95	$139.00
Purchase #6	$208.93	7.146%	$223.8601	$223.86	$223.85	$223.90
Purchase #7	$184.78	11.748%	$206.488	$206.49	$206.50	$206.50
7 purchase totals =	$1,087.95		$1,184.1231	$1,184.13	$1,184.15	$1,184.20