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	$73.81	9.243%	$80.6323	$80.63	$80.65	$80.60
Purchase #2	$171.29	4.859%	$179.613	$179.61	$179.60	$179.60
Purchase #3	$103.54	7.496%	$111.3014	$111.30	$111.30	$111.30
Purchase #4	$206.98	13.530%	$234.9844	$234.98	$235.00	$235.00
Purchase #5	$93.85	3.629%	$97.2558	$97.26	$97.25	$97.30
Purchase #6	$160.67	3.275%	$165.9319	$165.93	$165.95	$165.90
Purchase #7	$138.89	12.335%	$156.0221	$156.02	$156.00	$156.00
7 purchase totals =	$949.03		$1,025.7409	$1,025.73	$1,025.75	$1,025.70