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	$75.68	4.165%	$78.8321	$78.83	$78.85	$78.80
Purchase #2	$32.39	10.352%	$35.743	$35.74	$35.75	$35.70
Purchase #3	$190.45	3.583%	$197.2738	$197.27	$197.25	$197.30
Purchase #4	$89.90	9.874%	$98.7767	$98.78	$98.80	$98.80
Purchase #5	$210.60	11.682%	$235.2023	$235.20	$235.20	$235.20
Purchase #6	$204.55	12.241%	$229.589	$229.59	$229.60	$229.60
Purchase #7	$141.74	5.860%	$150.046	$150.05	$150.05	$150.00
7 purchase totals =	$945.31		$1,025.4629	$1,025.46	$1,025.50	$1,025.40