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	$211.67	10.201%	$233.2625	$233.26	$233.25	$233.30
Purchase #2	$25.61	10.406%	$28.275	$28.28	$28.30	$28.30
Purchase #3	$123.25	8.658%	$133.921	$133.92	$133.90	$133.90
Purchase #4	$72.45	6.765%	$77.3512	$77.35	$77.35	$77.40
Purchase #5	$232.67	4.126%	$242.27	$242.27	$242.25	$242.30
Purchase #6	$215.94	10.759%	$239.173	$239.17	$239.15	$239.20
Purchase #7	$122.38	4.513%	$127.903	$127.90	$127.90	$127.90
7 purchase totals =	$1,003.97		$1,082.1557	$1,082.15	$1,082.10	$1,082.30