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	$59.48	4.170%	$61.9603	$61.96	$61.95	$62.00
Purchase #2	$84.48	8.789%	$91.9049	$91.90	$91.90	$91.90
Purchase #3	$50.91	4.604%	$53.2539	$53.25	$53.25	$53.30
Purchase #4	$65.39	11.739%	$73.0661	$73.07	$73.05	$73.10
Purchase #5	$240.27	13.847%	$273.5402	$273.54	$273.55	$273.50
Purchase #6	$17.85	8.500%	$19.3673	$19.37	$19.35	$19.40
Purchase #7	$153.53	7.393%	$164.8805	$164.88	$164.90	$164.90
7 purchase totals =	$671.91		$737.9732	$737.97	$737.95	$738.10