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	$147.91	13.496%	$167.8719	$167.87	$167.85	$167.90
Purchase #2	$26.36	12.686%	$29.704	$29.70	$29.70	$29.70
Purchase #3	$150.54	11.279%	$167.5194	$167.52	$167.50	$167.50
Purchase #4	$165.83	5.214%	$174.4764	$174.48	$174.50	$174.50
Purchase #5	$249.77	6.291%	$265.483	$265.48	$265.50	$265.50
Purchase #6	$89.95	10.685%	$99.5612	$99.56	$99.55	$99.60
Purchase #7	$144.52	5.517%	$152.4932	$152.49	$152.50	$152.50
7 purchase totals =	$974.88		$1,057.1091	$1,057.10	$1,057.10	$1,057.20