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	$195.60	8.181%	$211.602	$211.60	$211.60	$211.60
Purchase #2	$212.90	4.441%	$222.3549	$222.35	$222.35	$222.40
Purchase #3	$125.50	9.419%	$137.3208	$137.32	$137.30	$137.30
Purchase #4	$155.41	10.834%	$172.2471	$172.25	$172.25	$172.20
Purchase #5	$190.60	9.285%	$208.2972	$208.30	$208.30	$208.30
Purchase #6	$136.69	4.440%	$142.759	$142.76	$142.75	$142.80
Purchase #7	$31.90	4.392%	$33.301	$33.30	$33.30	$33.30
7 purchase totals =	$1,048.60		$1,127.8820	$1,127.88	$1,127.85	$1,127.90