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	$229.28	7.404%	$246.2559	$246.26	$246.25	$246.30
Purchase #2	$60.50	12.339%	$67.9651	$67.97	$67.95	$68.00
Purchase #3	$139.54	7.825%	$150.459	$150.46	$150.45	$150.50
Purchase #4	$210.84	5.182%	$221.7657	$221.77	$221.75	$221.80
Purchase #5	$30.81	6.713%	$32.8783	$32.88	$32.90	$32.90
Purchase #6	$195.50	7.219%	$209.6131	$209.61	$209.60	$209.60
Purchase #7	$105.42	11.444%	$117.4843	$117.48	$117.50	$117.50
7 purchase totals =	$971.89		$1,046.4214	$1,046.43	$1,046.40	$1,046.60