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	$216.34	5.788%	$228.8618	$228.86	$228.85	$228.90
Purchase #2	$56.36	8.717%	$61.2729	$61.27	$61.25	$61.30
Purchase #3	$238.73	9.282%	$260.8889	$260.89	$260.90	$260.90
Purchase #4	$164.91	11.728%	$184.2506	$184.25	$184.25	$184.30
Purchase #5	$43.70	12.782%	$49.2857	$49.29	$49.30	$49.30
Purchase #6	$149.29	10.801%	$165.4148	$165.41	$165.40	$165.40
Purchase #7	$112.48	9.428%	$123.0846	$123.08	$123.10	$123.10
7 purchase totals =	$981.81		$1,073.0593	$1,073.05	$1,073.05	$1,073.20