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	$167.80	4.575%	$175.4769	$175.48	$175.50	$175.50
Purchase #2	$241.53	10.649%	$267.2505	$267.25	$267.25	$267.30
Purchase #3	$195.47	6.490%	$208.156	$208.16	$208.15	$208.20
Purchase #4	$56.98	5.112%	$59.8928	$59.89	$59.90	$59.90
Purchase #5	$168.92	3.376%	$174.6227	$174.62	$174.60	$174.60
Purchase #6	$165.25	3.775%	$171.4882	$171.49	$171.50	$171.50
Purchase #7	$15.86	4.653%	$16.598	$16.60	$16.60	$16.60
7 purchase totals =	$1,011.81		$1,073.4851	$1,073.49	$1,073.50	$1,073.60