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	$197.33	7.354%	$211.8416	$211.84	$211.85	$211.80
Purchase #2	$63.95	6.161%	$67.89	$67.89	$67.90	$67.90
Purchase #3	$141.32	13.269%	$160.0718	$160.07	$160.05	$160.10
Purchase #4	$155.32	7.778%	$167.4008	$167.40	$167.40	$167.40
Purchase #5	$100.75	7.247%	$108.0514	$108.05	$108.05	$108.10
Purchase #6	$176.64	12.113%	$198.0364	$198.04	$198.05	$198.00
Purchase #7	$88.95	12.318%	$99.9069	$99.91	$99.90	$99.90
7 purchase totals =	$924.26		$1,013.1989	$1,013.20	$1,013.20	$1,013.20