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	$127.81	4.653%	$133.757	$133.76	$133.75	$133.80
Purchase #2	$56.76	4.165%	$59.1241	$59.12	$59.10	$59.10
Purchase #3	$82.61	5.186%	$86.8942	$86.89	$86.90	$86.90
Purchase #4	$147.50	6.702%	$157.3855	$157.39	$157.40	$157.40
Purchase #5	$60.58	7.364%	$65.0411	$65.04	$65.05	$65.00
Purchase #6	$86.46	3.429%	$89.4247	$89.42	$89.40	$89.40
Purchase #7	$116.91	6.544%	$124.5606	$124.56	$124.55	$124.60
7 purchase totals =	$678.63		$716.1872	$716.18	$716.15	$716.20