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	$227.53	7.451%	$244.4833	$244.48	$244.50	$244.50
Purchase #2	$178.58	6.235%	$189.7145	$189.71	$189.70	$189.70
Purchase #3	$135.43	12.275%	$152.054	$152.05	$152.05	$152.10
Purchase #4	$93.78	7.511%	$100.8238	$100.82	$100.80	$100.80
Purchase #5	$71.81	3.695%	$74.4634	$74.46	$74.45	$74.50
Purchase #6	$173.34	7.252%	$185.9106	$185.91	$185.90	$185.90
Purchase #7	$179.88	3.832%	$186.773	$186.77	$186.75	$186.80
7 purchase totals =	$1,060.35		$1,134.2226	$1,134.20	$1,134.15	$1,134.30