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	$91.79	4.605%	$96.0169	$96.02	$96.00	$96.00
Purchase #2	$74.83	3.524%	$77.467	$77.47	$77.45	$77.50
Purchase #3	$131.42	10.705%	$145.4885	$145.49	$145.50	$145.50
Purchase #4	$33.57	4.520%	$35.0874	$35.09	$35.10	$35.10
Purchase #5	$60.92	7.615%	$65.5591	$65.56	$65.55	$65.60
Purchase #6	$71.39	13.841%	$81.2711	$81.27	$81.25	$81.30
Purchase #7	$190.49	7.149%	$204.1081	$204.11	$204.10	$204.10
7 purchase totals =	$654.41		$704.9981	$705.01	$704.95	$705.10