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	$126.64	4.739%	$132.6415	$132.64	$132.65	$132.60
Purchase #2	$92.75	11.765%	$103.662	$103.66	$103.65	$103.70
Purchase #3	$181.67	8.112%	$196.4071	$196.41	$196.40	$196.40
Purchase #4	$243.26	4.315%	$253.7567	$253.76	$253.75	$253.80
Purchase #5	$215.71	3.614%	$223.5058	$223.51	$223.50	$223.50
Purchase #6	$235.82	6.399%	$250.9101	$250.91	$250.90	$250.90
Purchase #7	$48.42	13.864%	$55.1329	$55.13	$55.15	$55.10
7 purchase totals =	$1,144.27		$1,216.0161	$1,216.02	$1,216.00	$1,216.00