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	$182.37	4.747%	$191.0271	$191.03	$191.05	$191.00
Purchase #2	$20.39	6.739%	$21.7641	$21.76	$21.75	$21.80
Purchase #3	$45.76	11.214%	$50.8915	$50.89	$50.90	$50.90
Purchase #4	$65.45	4.858%	$68.6296	$68.63	$68.65	$68.60
Purchase #5	$132.97	6.623%	$141.7766	$141.78	$141.80	$141.80
Purchase #6	$167.53	4.689%	$175.3855	$175.39	$175.40	$175.40
Purchase #7	$33.45	11.364%	$37.2513	$37.25	$37.25	$37.30
7 purchase totals =	$647.92		$686.7257	$686.73	$686.80	$686.80