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	$189.98	3.256%	$196.1657	$196.17	$196.15	$196.20
Purchase #2	$160.41	3.374%	$165.8222	$165.82	$165.80	$165.80
Purchase #3	$30.79	3.649%	$31.9135	$31.91	$31.90	$31.90
Purchase #4	$156.97	5.569%	$165.7117	$165.71	$165.70	$165.70
Purchase #5	$236.57	9.436%	$258.8927	$258.89	$258.90	$258.90
Purchase #6	$23.68	7.422%	$25.4375	$25.44	$25.45	$25.40
Purchase #7	$162.36	11.236%	$180.6028	$180.60	$180.60	$180.60
7 purchase totals =	$960.76		$1,024.5461	$1,024.54	$1,024.50	$1,024.50