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	$147.68	3.601%	$152.998	$153.00	$153.00	$153.00
Purchase #2	$172.48	10.787%	$191.0854	$191.09	$191.10	$191.10
Purchase #3	$147.97	4.674%	$154.8861	$154.89	$154.90	$154.90
Purchase #4	$33.89	10.344%	$37.3956	$37.40	$37.40	$37.40
Purchase #5	$171.39	12.352%	$192.5601	$192.56	$192.55	$192.60
Purchase #6	$62.71	5.435%	$66.1183	$66.12	$66.10	$66.10
Purchase #7	$190.65	13.495%	$216.3782	$216.38	$216.40	$216.40
7 purchase totals =	$926.77		$1,011.4217	$1,011.44	$1,011.45	$1,011.50