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	$83.82	10.111%	$92.295	$92.30	$92.30	$92.30
Purchase #2	$130.88	9.271%	$143.0139	$143.01	$143.00	$143.00
Purchase #3	$127.25	9.445%	$139.2688	$139.27	$139.25	$139.30
Purchase #4	$45.65	8.454%	$49.5093	$49.51	$49.50	$49.50
Purchase #5	$150.53	6.513%	$160.334	$160.33	$160.35	$160.30
Purchase #6	$136.63	7.718%	$147.1751	$147.18	$147.20	$147.20
Purchase #7	$19.50	6.299%	$20.7283	$20.73	$20.75	$20.70
7 purchase totals =	$694.26		$752.3244	$752.33	$752.35	$752.30