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	$89.91	3.872%	$93.3913	$93.39	$93.40	$93.40
Purchase #2	$69.69	5.613%	$73.6017	$73.60	$73.60	$73.60
Purchase #3	$31.51	11.736%	$35.208	$35.21	$35.20	$35.20
Purchase #4	$30.33	11.259%	$33.7449	$33.74	$33.75	$33.70
Purchase #5	$97.78	3.223%	$100.9314	$100.93	$100.95	$100.90
Purchase #6	$20.83	13.404%	$23.6221	$23.62	$23.60	$23.60
Purchase #7	$86.50	6.278%	$91.9305	$91.93	$91.95	$91.90
7 purchase totals =	$426.55		$452.4299	$452.42	$452.45	$452.30