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	$158.99	5.194%	$167.2479	$167.25	$167.25	$167.20
Purchase #2	$195.48	7.198%	$209.5507	$209.55	$209.55	$209.60
Purchase #3	$209.68	6.769%	$223.8732	$223.87	$223.85	$223.90
Purchase #4	$37.47	3.466%	$38.7687	$38.77	$38.75	$38.80
Purchase #5	$220.58	10.443%	$243.6152	$243.62	$243.60	$243.60
Purchase #6	$126.78	10.856%	$140.5432	$140.54	$140.55	$140.50
Purchase #7	$145.59	3.317%	$150.4192	$150.42	$150.40	$150.40
7 purchase totals =	$1,094.57		$1,174.0181	$1,174.02	$1,173.95	$1,174.00