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	$50.61	6.162%	$53.7286	$53.73	$53.75	$53.70
Purchase #2	$52.61	7.823%	$56.7257	$56.73	$56.75	$56.70
Purchase #3	$249.72	7.370%	$268.1244	$268.12	$268.10	$268.10
Purchase #4	$88.83	10.840%	$98.4592	$98.46	$98.45	$98.50
Purchase #5	$208.89	11.551%	$233.0189	$233.02	$233.00	$233.00
Purchase #6	$64.72	7.208%	$69.385	$69.39	$69.40	$69.40
Purchase #7	$26.83	6.383%	$28.5426	$28.54	$28.55	$28.50
7 purchase totals =	$742.21		$807.9844	$807.99	$808.00	$807.90