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	$173.90	12.740%	$196.0549	$196.05	$196.05	$196.10
Purchase #2	$176.34	5.149%	$185.4197	$185.42	$185.40	$185.40
Purchase #3	$88.51	4.574%	$92.5584	$92.56	$92.55	$92.60
Purchase #4	$107.72	11.225%	$119.8116	$119.81	$119.80	$119.80
Purchase #5	$6.32	10.629%	$6.9918	$6.99	$7.00	$7.00
Purchase #6	$31.56	12.445%	$35.4876	$35.49	$35.50	$35.50
Purchase #7	$130.27	12.454%	$146.4938	$146.49	$146.50	$146.50
7 purchase totals =	$714.62		$782.8178	$782.81	$782.80	$782.90