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	$159.95	9.818%	$175.6539	$175.65	$175.65	$175.70
Purchase #2	$106.75	6.278%	$113.4518	$113.45	$113.45	$113.50
Purchase #3	$67.37	6.478%	$71.7342	$71.73	$71.75	$71.70
Purchase #4	$89.71	9.847%	$98.5437	$98.54	$98.55	$98.50
Purchase #5	$215.28	3.598%	$223.0258	$223.03	$223.05	$223.00
Purchase #6	$249.75	4.688%	$261.4583	$261.46	$261.45	$261.50
Purchase #7	$145.40	4.431%	$151.8427	$151.84	$151.85	$151.80
7 purchase totals =	$1,034.21		$1,095.7104	$1,095.70	$1,095.75	$1,095.70