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	$46.54	7.749%	$50.1464	$50.15	$50.15	$50.10
Purchase #2	$67.85	6.856%	$72.5018	$72.50	$72.50	$72.50
Purchase #3	$31.39	12.740%	$35.3891	$35.39	$35.40	$35.40
Purchase #4	$166.52	13.179%	$188.4657	$188.47	$188.45	$188.50
Purchase #5	$27.76	8.486%	$30.1157	$30.12	$30.10	$30.10
Purchase #6	$23.61	9.630%	$25.8836	$25.88	$25.90	$25.90
Purchase #7	$29.45	9.507%	$32.2498	$32.25	$32.25	$32.20
7 purchase totals =	$393.12		$434.7521	$434.76	$434.75	$434.70