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	$168.58	4.147%	$175.571	$175.57	$175.55	$175.60
Purchase #2	$151.81	9.247%	$165.8479	$165.85	$165.85	$165.80
Purchase #3	$39.37	3.478%	$40.7393	$40.74	$40.75	$40.70
Purchase #4	$147.49	9.675%	$161.7597	$161.76	$161.75	$161.80
Purchase #5	$50.64	7.478%	$54.4269	$54.43	$54.45	$54.40
Purchase #6	$83.94	6.652%	$89.5237	$89.52	$89.50	$89.50
Purchase #7	$62.53	7.668%	$67.3248	$67.32	$67.30	$67.30
7 purchase totals =	$704.36		$755.1933	$755.19	$755.15	$755.10