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	$89.60	13.389%	$101.5965	$101.60	$101.60	$101.60
Purchase #2	$215.63	9.471%	$236.0523	$236.05	$236.05	$236.10
Purchase #3	$35.56	11.459%	$39.6348	$39.63	$39.65	$39.60
Purchase #4	$32.83	13.595%	$37.2932	$37.29	$37.30	$37.30
Purchase #5	$89.42	6.721%	$95.4299	$95.43	$95.45	$95.40
Purchase #6	$99.95	9.543%	$109.4882	$109.49	$109.50	$109.50
Purchase #7	$97.40	9.380%	$106.5361	$106.54	$106.55	$106.50
7 purchase totals =	$660.39		$726.0310	$726.03	$726.10	$726.00