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	$219.68	6.850%	$234.7281	$234.73	$234.75	$234.70
Purchase #2	$228.37	11.472%	$254.5686	$254.57	$254.55	$254.60
Purchase #3	$60.75	11.413%	$67.6834	$67.68	$67.70	$67.70
Purchase #4	$90.95	7.767%	$98.0141	$98.01	$98.00	$98.00
Purchase #5	$61.76	13.171%	$69.8944	$69.89	$69.90	$69.90
Purchase #6	$145.39	13.663%	$165.2546	$165.25	$165.25	$165.30
Purchase #7	$213.58	9.265%	$233.3682	$233.37	$233.35	$233.40
7 purchase totals =	$1,020.48		$1,123.5114	$1,123.50	$1,123.50	$1,123.60