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	$164.64	11.796%	$184.0609	$184.06	$184.05	$184.10
Purchase #2	$80.56	11.235%	$89.6109	$89.61	$89.60	$89.60
Purchase #3	$28.63	4.405%	$29.8912	$29.89	$29.90	$29.90
Purchase #4	$101.77	8.805%	$110.7308	$110.73	$110.75	$110.70
Purchase #5	$115.82	6.339%	$123.1618	$123.16	$123.15	$123.20
Purchase #6	$234.89	4.539%	$245.5517	$245.55	$245.55	$245.60
Purchase #7	$232.95	4.678%	$243.8474	$243.85	$243.85	$243.80
7 purchase totals =	$959.26		$1,026.8547	$1,026.85	$1,026.85	$1,026.90