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	$193.40	11.425%	$215.496	$215.50	$215.50	$215.50
Purchase #2	$246.46	8.676%	$267.8429	$267.84	$267.85	$267.80
Purchase #3	$54.76	12.749%	$61.7414	$61.74	$61.75	$61.70
Purchase #4	$42.73	5.554%	$45.1032	$45.10	$45.10	$45.10
Purchase #5	$151.78	6.476%	$161.6093	$161.61	$161.60	$161.60
Purchase #6	$246.39	7.455%	$264.7584	$264.76	$264.75	$264.80
Purchase #7	$33.87	4.728%	$35.4714	$35.47	$35.45	$35.50
7 purchase totals =	$969.39		$1,052.0226	$1,052.02	$1,052.00	$1,052.00