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	$217.57	13.542%	$247.0333	$247.03	$247.05	$247.00
Purchase #2	$85.63	7.397%	$91.9641	$91.96	$91.95	$92.00
Purchase #3	$145.31	13.253%	$164.5679	$164.57	$164.55	$164.60
Purchase #4	$208.71	10.158%	$229.9108	$229.91	$229.90	$229.90
Purchase #5	$144.66	4.718%	$151.4851	$151.49	$151.50	$151.50
Purchase #6	$160.93	7.311%	$172.6956	$172.70	$172.70	$172.70
Purchase #7	$101.47	7.807%	$109.3918	$109.39	$109.40	$109.40
7 purchase totals =	$1,064.28		$1,167.0486	$1,167.05	$1,167.05	$1,167.10