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	$43.47	3.437%	$44.9641	$44.96	$44.95	$45.00
Purchase #2	$200.29	11.560%	$223.4435	$223.44	$223.45	$223.40
Purchase #3	$203.39	7.596%	$218.8395	$218.84	$218.85	$218.80
Purchase #4	$221.68	7.712%	$238.776	$238.78	$238.80	$238.80
Purchase #5	$233.45	13.437%	$264.8187	$264.82	$264.80	$264.80
Purchase #6	$35.89	8.540%	$38.955	$38.96	$38.95	$39.00
Purchase #7	$144.61	12.659%	$162.9162	$162.92	$162.90	$162.90
7 purchase totals =	$1,082.78		$1,192.7130	$1,192.72	$1,192.70	$1,192.70