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	$109.64	4.640%	$114.7273	$114.73	$114.75	$114.70
Purchase #2	$248.39	6.513%	$264.5676	$264.57	$264.55	$264.60
Purchase #3	$58.42	4.702%	$61.1669	$61.17	$61.15	$61.20
Purchase #4	$110.87	5.204%	$116.6397	$116.64	$116.65	$116.60
Purchase #5	$240.30	10.741%	$266.1106	$266.11	$266.10	$266.10
Purchase #6	$242.83	4.786%	$254.4518	$254.45	$254.45	$254.50
Purchase #7	$160.71	13.393%	$182.2339	$182.23	$182.25	$182.20
7 purchase totals =	$1,171.16		$1,259.8978	$1,259.90	$1,259.90	$1,259.90