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	$193.83	7.519%	$208.4041	$208.40	$208.40	$208.40
Purchase #2	$224.51	13.215%	$254.179	$254.18	$254.20	$254.20
Purchase #3	$35.43	6.762%	$37.8258	$37.83	$37.85	$37.80
Purchase #4	$147.28	12.429%	$165.5854	$165.59	$165.60	$165.60
Purchase #5	$239.82	13.807%	$272.9319	$272.93	$272.95	$272.90
Purchase #6	$105.70	8.550%	$114.7374	$114.74	$114.75	$114.70
Purchase #7	$145.73	3.548%	$150.9005	$150.90	$150.90	$150.90
7 purchase totals =	$1,092.30		$1,204.5641	$1,204.57	$1,204.65	$1,204.50