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	$89.54	13.394%	$101.533	$101.53	$101.55	$101.50
Purchase #2	$74.76	3.340%	$77.257	$77.26	$77.25	$77.30
Purchase #3	$79.98	9.465%	$87.5501	$87.55	$87.55	$87.60
Purchase #4	$189.60	5.507%	$200.0413	$200.04	$200.05	$200.00
Purchase #5	$79.38	4.118%	$82.6489	$82.65	$82.65	$82.60
Purchase #6	$238.92	10.174%	$263.2277	$263.23	$263.25	$263.20
Purchase #7	$83.66	7.134%	$89.6283	$89.63	$89.65	$89.60
7 purchase totals =	$835.84		$901.8863	$901.89	$901.95	$901.80