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	$89.25	6.512%	$95.062	$95.06	$95.05	$95.10
Purchase #2	$62.81	4.511%	$65.6434	$65.64	$65.65	$65.60
Purchase #3	$208.61	7.129%	$223.4818	$223.48	$223.50	$223.50
Purchase #4	$138.87	6.209%	$147.4924	$147.49	$147.50	$147.50
Purchase #5	$158.26	13.451%	$179.5476	$179.55	$179.55	$179.50
Purchase #6	$5.90	4.520%	$6.1667	$6.17	$6.15	$6.20
Purchase #7	$160.55	12.356%	$180.3876	$180.39	$180.40	$180.40
7 purchase totals =	$824.25		$897.7815	$897.78	$897.80	$897.80