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	$97.64	8.120%	$105.5684	$105.57	$105.55	$105.60
Purchase #2	$131.90	7.362%	$141.6105	$141.61	$141.60	$141.60
Purchase #3	$168.56	3.818%	$174.9956	$175.00	$175.00	$175.00
Purchase #4	$186.77	6.647%	$199.1846	$199.18	$199.20	$199.20
Purchase #5	$103.42	8.662%	$112.3782	$112.38	$112.40	$112.40
Purchase #6	$116.62	6.702%	$124.4359	$124.44	$124.45	$124.40
Purchase #7	$136.43	11.707%	$152.4019	$152.40	$152.40	$152.40
7 purchase totals =	$941.34		$1,010.5751	$1,010.58	$1,010.60	$1,010.60