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	$215.81	3.120%	$222.5433	$222.54	$222.55	$222.50
Purchase #2	$142.63	4.650%	$149.2623	$149.26	$149.25	$149.30
Purchase #3	$135.56	3.792%	$140.7004	$140.70	$140.70	$140.70
Purchase #4	$122.43	8.142%	$132.3983	$132.40	$132.40	$132.40
Purchase #5	$67.74	7.681%	$72.9431	$72.94	$72.95	$72.90
Purchase #6	$100.89	13.263%	$114.271	$114.27	$114.25	$114.30
Purchase #7	$234.48	4.160%	$244.2344	$244.23	$244.25	$244.20
7 purchase totals =	$1,019.54		$1,076.3528	$1,076.34	$1,076.35	$1,076.30